M ntADE 
GenCol1 


TP 271 
.S5 

Copy 2 
















w 


!&«»> ^ 




lipv ^ ‘Hfe? <^ \WfftJ 

^ 0, /^v;'°i' ,n *5*°^*^ *5% 

^Wm? .^ v ^. ITOw * J>%. 1>wm: 


& % V'^’V <o 

cor - ,\< • * '&; V • ">°!c 

,v -V *•. 

oV 4 &b isssr * 

_ v 0 ^°-\ \w\° ^ 0 > 

.^oo ; 3. ^ . 

w * 

°*W^W£ •^’'V, 5 

• • vV 


;*p ^ v 
% ’ # w/ ^ V V°°J^ 

■:v° * * * * * -« “**^ ' 0 

»- °J^r." 


t^^P’o <P°<c r?PWB* >?4 -lff§?* 0 W 
w ^«oo*^,.„ °°* **.. 1 * ***°?.. * > \** ° »-» 

* \^P/ </\ 01 

( \'° * l * jj? > \****?+o* * ‘ S WV 1, *<V° ’ ^/ c o»c,\ ' ' 

* t. rr * ^ * * u o Sr V *. Wtf rV » ** 

^ 1 0 41PNit| * ^ov * JPf^f * v*d* 0 ^ 

\„ ^ A X <* A/R$W H -P? rt. C\* <X Va -: -' U^S\a ^ /^ <* A/R&H US© rt r 





^ zwm°* ‘ 

x - <bJ> J O 

<£> % * 


% v^ ^ 

u « 

* iP-tj, * 

*y <> Q*» </> Mi\\\\v * v 



P A> *' 

4 


* r J Z ° ^ Z MrsM p 


\° v ^ <j 


o,V V »” 


jV 

y a/ v- r* ^O C^i ^ ^ 

* Wr^fe 0 sW?- 

0 vV^t z 


w^\w ^ \ vU p/ ^ v \ ^ 

" * * >t*i^vv° * ^ o^^ nc *!v ' * s >\- l, »/<£ 

: -*^i=»-*^fe*- ^ ?*s. 


W. * 


A . X 



* OV 

* 1W1 . WCS . 

■"’ ^*.\"’aA 
^ -•'^•V^.* Jte; <W •* 


, „ J KlM~U£i 2 ^ S 

■ ° 

'.\v^‘* 

* jO-*^ 

ojSill'* 

■Jo ■r, 


cf?^n 

<£> ^ * 

fv° * V^r ^ V* • 

■ V 

^ *32m$ s°\ * 


\ \ A - 
° ^ s 


^ o 


* * Or ** *\ <%y/iW -v v o <, 

: W A-V-' mk\%4>i* 

'*■ v^'v <,? 

*/V 0>1, / t 


^ * o 


^ ° 

" ,a/ ^ <v ^ °„ 

. o<^v * * * 1 

W «b^ 

“ . #+K 

❖ -O **» 





7 T^ 
* ^ 


*.<r Vvr^ 

- 




I %<- 

> v^sr^/ 

r *<D. -*? 

»i* O -■' 


V^IEF* * # a^ 0 * AO, t^Jf* ,CV 

* t A?gPi%. -O b> 't^ o *&%!$* * r> ^ 


* L, */<i 


v <* 

<<#/o*‘* ' 6 


•*.\ , 

* „ 

^ & c ONO, 0 4* n ■* " * « W, <^ - 

; *°^ *Jll§\ o o°* vS®; ^ ’f§lF° ^ 

o^^fw “ «y^” J ^ * ®IK^ * O'^' o«W* «^ >J ^>- * SK3 

V° * i *V°*° No «*\^ * * i, */v° * * * 5 

T- ry «)■ _^vv ^ ^r) ^ <w)^l ■* Tw rV » ^ *j» \3 ^ 

<1 ^ ^ 4r ** MI/^3> *. ^ ° c^AV& -» - M 

v*c y 0 «• ^OV 


o 
* 

^.o\'*..-* 

* '». A>- » 

O *«&<£ O 


,'°*^0^ cO-«> 0 ^* 

»A* ^ 


AK' ^ •> tX. 0 N&AIXVSN^ . At- V ~ 

^ ^aO° V^ono^ °0>^ 

o^% s<1 *^ v <y +'*°p %> 


<C 


Z 0 7 - > 

«lfS? ° ° 1 

VBgSrf & ^ °J 
.w.O/ 


* 2 
1 « . _1 


J>- 

S-X* c,** * 



* <gf ^ < 


• s ^ 


V<<r.f 

t> ^OV <* 

;.v°^ * 




£>% 


<f? v. 



>*, ‘-ZVJAf^V A, rN A*» J> MsSA 3 ^ A v 7» 

O'” *>°»» * * ;t V M - s ° 








Bulletin 51 




department of the interior 

BUREAU OF MINES 

JOSEPH A. HOLMES, Director 


THE ANALYSIS OF 
BLACK POWDER AND DYNAMITE 



WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1913 


Montgraph 


/-v/ 


» * .x. 


,rS : " 

4 l .V •-■-'■ ’ 






/ 


Bulletin 51 


DEPARTMENT OF THE INTERIOR 

BUREAU OF MINES 

JOSEPH A. HOLMES, Director 


THE ANALYSIS OF 
BLACK POWDER AND DYNAMITE 


y o 2 - 


BY 


WALTER O. SNELLING and C. G. STORM 

M ' 



WASHINGTON 

GOVERNMENT PRINTING OFFICE 
J913 




First edition . March , 1913. 


D. OF D, 
MAY 17 1913 


» 

« 


t* 


- * » 


I3-ZSU0 




CONTENTS. 


£ 

Page. 


Introduction. 5 

Dynamite. 6 

Physical examination. 7 

Determination of gravimetric density. 7 

Test for liability of exudation. 8 

Forty-degree test for exudation. 8 

Pressure test for exudation. 9 

Centrifugal test for exudation. 9 

Test for stability. 10 

Abel test. 10 

Caramel standard tint paper. 11 

Preparation of paper for Abel test. 12 

Sampling. 12 

Chemical examination. 16 

Qualitative examination. 16 

Determination of moisture. 19 

In ordinary desiccators. 20 

In vacuum desiccators. 27 

In a dry-air current. 28 

Summary. 29 

Extraction with ether. 30 

Reflux-condenser method. 30 

Suction method. 32 

Comparative extractions with anhydrous and U. S. P. (96 per cent) 

ether.*.-. 33 

Effect of moisture in dynamite on extraction with ether. 34 

Determination of nitroglycerin. 35 

The nitrometer. 35 

Procedure. 38 

Evaporation in the bell-jar evaporator. 40 

Determinations of sulphur, resins, etc. 41 

Extraction with water. 43 

Determination of alkaline nitrates. 44 

Determination of alkaline nitrates by means of the nitrometer- 45 

Extraction with acid. 45 

Determination of calcium. 46 

Determination of magnesium. 46 

Determination of zinc. 46 

Determination of starch. 47 

Examination of insoluble residue. 49 

Determination of wood pulp, etc. 49 

Determination of ash.. —. 50 

Variations due to method of analysis. 50 

Discussion of analyses. 52 

Moisture. 52 

Nitroglycerin. 52 

Potassium nitrate. 53 

Calcium carbonate. 53 

Wood pulp. 53 


3 


















































4 


CONTENTS. 


Page. 

Gelatin dynamite. 54 

Sampling. 54 

Sulphur. 55 

Nitrocellulose. 55 

Ammonia dynamite. 57 

Low-freezing dynami te. 61 

Determination of nitrosubstitution compounds. 61 

Granulated nitroglycerin powder... 64 

Black powder. 66 

Physical examination. 66 

Granulation or average size of grains. 66 

Gravimetric density. 67 

Absolute density. 67 

Sampling. 68 

Chemical examination. 69 

Determination of moisture. 69 

Extraction with water; determination of nitrates..:. 70 

Extraction with carbon disulphide; determination of sulphur. 72 

Insoluble residue, charcoal. 72 

Determination of ash. 72 

Bureau of Mines method of analysis. 76 

Publications on mine accidents and tests of explosives. 77 


ILLUSTRATIONS. 


Plate I. A, Apparatus for Abel heat test; B, Centrifuge for exudation test of 

dynamite. 10 

II. A , Wiley extractor; B, Gravimetric balance. 32 

III. Nitrometer. 36 

IV. A, Wood pulp No. 1; B, Wood pulp No. 2; C, Sawdust; D, In¬ 

fusorial earth No. 1; E. Infusorial earth No. 2; F, Crude fiber from 

wheat middlings. 50 

V. A, Cellulose (cotton); B , Nitrocellulose; C, Wheat flour (fine); 

D, Wheat flour (fine) and wood pulp; E, Wheat flour (middlings); 

F, Corn meal. 52 

Figure 1. Influence of temperature on determination of moisture in 60 per cent 

dynamite by desiccation over sulphuric acid. 23 

2. Results of desiccation of 60 per cent dynamite over calcium chloride 

and over sulphuric acid at room temperatures. 25 

3. Result of exposure of dry 60 per cent dynamite in a desiccator at 

33° to 35° C. without desiccating agent. 26 

4. Drying tube. 30 

5. Densimeter.*. 68 




































THE ANALYSIS OF BLACK POWDER AND DYNAMITE. 


By Walter O. Snelling and C. G. Storm. 


INTRODUCTION. 

Although descriptions of the methods of analysis of explosives are 
to be found in many books on explosives, and in works on engineer¬ 
ing chemistry or chemical analysis, most of these descriptions are 
incomplete and lacking in details. The methods of analysis employed 
in the laboratories of most explosives factories are frequently treated 
as trade secrets, and very little information is published from such 
laboratories. 

This bulletin outlines the methods of analysis that are used by 
the Bureau of Mines in the examination of certain classes of explo¬ 
sives. The present form of most of these methods has been worked 
out in the bureau’s explosives laboratory. The methods employed 
by Prof. C. E. Munroe were taken as a basis, and were elaborated to 
meet the demands incident to the treatment of complicated mix¬ 
tures and to the development of the explosives art. A subsequent 
bulletin will discuss the methods of analysis of “ permissible” 
explosives, many of the latter being of decidedly complicated char¬ 
acter and requiring special treatment. This bulletin presents the 
methods of analysis of “ordinary” dynamite, and the ammonia, 
gelatin, low-freezing, and granular dynamites, and the common 
grades of black gunpowder and blafck blasting powder. The bulletin 
is published by the bureau for the information of all persons inter¬ 
ested in explosives and their safe and efficient use in mining work. 

As the term ‘‘ordinary” dynamite, though much used, has no 
conventional meaning, and may be used to cover a wide variety of 
compositions of matter, it may be noted that the standard dynamite 
used at the Pittsburgh testing station is a good example of the 
“ordinary” dynamite known in this country. This testing station 
dynamite has the following composition: 

Composition of Pittsburgh testing station dynamite. 

Per cent. 


Nitroglycerin. 40 

Sodium nitrate. 44 

Wood pulp. 15 


Calcium carbonate. 


5 








6 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


As most permissible explosives contain only the constituents 
found generally in the various types of ordinary dynamite, the 
chemist will usually find it possible to analyze such explosives either 
wholly or partly by following the general methods of analysis here 
given for the type of explosive that seems most closely related to the 
one under examination. The methods of extraction with ether, 
with water, etc., here outlined are general methods which are applied 
with equal success to all classes of explosives, and therefore by the 
use of these general methods, following a thorough qualitative 
examination, little difficulty should be met except with those classes 
of permissible explosives that contain large amounts of salts holding 
water of crystallization, such as alum and magnesium sulphate, or 
those containing an unusual number of uncommon constituents. 
Even with such explosives, however, if the information desired is 
principally in regard to the percentages of explosive ingredients 
(nitroglycerin, ammonium nitrate, etc.), the methods outlined in 
this bulletin may be satisfactorily followed. 

DYNAMITE. 

“Ordinary” dynamite consists essentially of nitroglycerin absorbed 
in some porous material. Owing to its physical condition and its 
extreme sensitiveness to shock, liquid nitroglycerin is not suitable 
for use as an explosive in-mining and quarrying, but when nitro¬ 
glycerin is absorbed in a porous material a more or less plastic mass 
is obtained which is far less sensitive to shock than liquid nitro¬ 
glycerin, although, when properly fired by means of a detonator, it 
retains most of the explosive properties of nitroglycerin. Among 
the many substances that have been used as absorbents for nitro¬ 
glycerin are sawdust, wood pulp, ground mica, and infusorial earth 
(kieselguhr), or mixtures of these substances with alkaline nitrates 
and other substances. 

It is usual to classify absorbents for nitroglycerin as active and 
inactive. Pulverized gunpowder, for example, or mixtures of wood 
pulp with sodium nitrate or other oxidizing agents, represent 
“ active ’ 1 absorbents, whereas mica, kieselguhr and similar materials, 
which play no part in the explosive reactions and which are employed 
merely to absorb or retain the liquid nitroglycerin, form the so-called 
“inactive” absorbents. 

The type of dynamite most generally used to-day consists of nitro¬ 
glycerin absorbed in a mixture of wood pulp and sodium nitrate, 
and to this mixture is usually added a small amount of some antacid 
such as calcium carbonate, magnesium carbonate, or zinc oxide. 
This antacid is added in the belief that it increases the stability of 
the resulting explosive by neutralizing such small amounts of free 


DYNAMITE. 7 

acid as may be produced by the decomposition of the nitroglycerin 
during long storage. 

The analysis of dynamite is best carried out by first separating, 
with ether or some other appropriate solvent, the nitroglycerin from 
the dope in which it is absorbed. After the nitroglycerin has been 
thus removed, the soluble nitrate in the dope may be removed by 
dissolving in water; the antacid may then be dissolved in dilute 
acid, and the residue insoluble in ether, water, dilute acid, etc., 
may be directly determined by weight. 

In its simplest form, therefore, the analysis of dynamite consists 
in the removal of the constituent materials, one by one, through the 
use of appropriate solvents. Dynamites of the most complicated 
composition may usually be analyzed in this way, through selective 
solution. In the present paper the methods of analyzing ordinary 
types of dynamite are discussed, and those that have been found 
best in an experience covering several thousand analyses are stated. 

PHYSICAL EXAMINATION. 

Upon receiving a sample of explosive for analysis it is desirable 
to record full information in regard to the size and weight of each 
cartridge, with a complete copy of any lettering that may appear on 
the wrapper. It is also advisable to record the nature of the outer 
wrapping paper (such as ordinary paper, parchmentized paper, 
or paper coated with paraffin), and whether the cartridge has been 
redipped; that is, placed in a paraffin bath after being filled. 
Whether a cartridge has been redipped can usually be determined 
by carefully opening the wrapper. If there is a greater thickness 
of paraffin near the edge where the sheet overlaps, or if the overlap¬ 
ping edge is attached to the adjacent portions of the paper by means 
of an adhering deposit of paraffin, it may be assumed that the cart¬ 
ridge has been redipped. 

DETERMINATION OF GRAVIMETRIC DENSITY. 

It is possible to determine approximately the gravimetric density 
or apparent specific gravity of a cartridge of explosive by measuring 
carefully the length and circumference of the cartridge, calculating 
from these figures the volume in cubic centimeters, and then dividing 
the weight in grams of the cartridge by this figure. However, 
experiments made at the bureau's explosives laboratory have shown 
that even with the most careful measurements the figures thus 
obtained are liable to be in error by as much as 10 to 20 per cent, 
a difference entirely too great to make the method permissible for 
exact work. With some redipped cartridges weighing in water has 
given satisfactory results, but cartridges seldom have a coating of 


8 


ANALYSIS OF BLACK POWDEB AND DYNAMITE. 


paraffin so complete as to permit the use of this method. Accord¬ 
ingly a method was sought that would at all times give satisfactory 
results even with cartridges that had not been redipped. 

The volume of the cartridge can be determined conveniently 
by using sand instead of water as the measuring material. A 
weighed glass cylinder about 30 cm. high and 5 cm. in inside diameter 
is filled with fine sand (preferably sea sand) that has been sifted 
through a 60-mesh sieve. A straight edge is drawn across the top 
of the cylinder, the level of the sand being left flush with the top 
edge, and the weight of the cylinder and contained sand is determined. 
From this weight the weight of the cylinder is subtracted and the 
result is the weight of the sand, which, divided by the weight of 
water required to fill the cylinder, gives the apparent specific gravity 
of the sand used. All the sand except enough to fill the cylinder to 
a depth of about 1 inch is now poured out, a weighed cartridge of 
the explosive is placed in the cylinder, and sand added until the 
cylinder is filled flush to the top as before, when it is struck with the 
straight edge and then the weight of cylinder and sand and cartridge 
is noted. From these figures the weight of sand displaced by the 
cartridge is found. This weight divided by the apparent specific 
gravity of the sand gives the volume of the cartridge. The weight 
of the cartridge divided by its volume gives its apparent specific 
gravity or gravimetric density. This determination leaves the car¬ 
tridge in condition for use in sampling, if desired. 

In making this determination care should be taken that the cylinder 
is filled each time in exactly the same manner, the sand being poured 
in slowly and not packed by jolting, shaking or otherwise. Repeated 
determinations of the weight of sand required to just fill the cylinder 
will prove that with proper care uniform results may be obtained; in 
practice this method has been found to be both rapid and exact. 

TEST FOR LIABILITY OF EXUDATION. 

To determine whether there is liability of leakage of nitroglycerin 
from cartridges containing this explosive, it is always advisable to 
make an exudation test, which indicates the amount of nitroglycerin 
that may be lost by the explosive tested under prescribed condi¬ 
tions. The tests most commonly used for this purpose are the 40° 
test, the pressure test, and the centrifugal test. 

40° TEST FOR EXUDATION. 

In the 40° test a cartridge of the explosive under examination is 
placed in a vertical position in an oven heated to 40° C. Some small 
perforations are made in the wrapper at the ends of the cartridge, 
and the cartridge is then placed on end on a small wire tripod in a 


DYNAMITE. 


9 


small glass beaker or cylinder. The whole is then placed for six days 
in an oven maintained at a constant temperature of 40° C. At the 
end of this time an examination is made to see if any leakage of 
nitroglycerin in the form of drops has occurred. Such leakage may 
be taken as evidence that there is too much nitroglycerin in the 
explosive for the amount of absorbent material present, or that the 
dopQ used is deficient in absorbing capacity. 

PRESSURE TEST FOR EXUDATION. 

Before the centrifugal test was employed, it was customary to use a 
pressure test for exudation which consisted in exposing a sample of the 
dynamite to a definite pressure produced by a weight on a lever arm, 
and determining the amount of nitroglycerin thereby forced out of 
the dynamite. Many modifications of this test have been tried, in 
which cotton, blotting paper, or other absorbent material have been 
used to hold the nitroglycerin forced out from the explosive. The 
pressure test is unreliable and hence is not satisfactory in use. For 
example, by this test an explosive that contains a certain amount of 
a mixture of sawdust and wood pulp shows less exudation than one 
in which the same amount of absorbent is used in the form of wood 
pulp alone, a result that is clearly incorrect, since the absorbing 
power of wood pulp is much greater than that of sawdust. The reason 
for the more favorable result when the absorbent contains sawdust is 
that the particles of sawdust are packed together to form a cellular 
mass, which incloses the particles of wood pulp holding the nitro¬ 
glycerin, thereby in a great measure protecting them from pressure. 

CENTRIFUGAL TEST FOR EXUDATION. 

The use of centrifugal force as a means of measuring the complete¬ 
ness with which nitroglycerin is absorbed in an explosive was some 
years ago suggested to Col. B. W. Dunn, chief inspector of the bureau 
for the safe transportation of explosives, by T. J. Wrampelmeier, an 
inspector in that bureau, and a device for testing the value of this 
method was made use of by C. P. Beistle,® chief chemist of that 
bureau. The method employed was to place the explosive, together 
with a perforated disk of vulcanite and an absorbent material such 
as cotton, within a glass tube, the tube being then placed in a cen¬ 
trifuge. The increase in weight of the cotton after rotation was 
taken as a measure of the amount of nitroglycerin lost by the explo¬ 
sive during the process. This apparatus gives much more satisfac¬ 
tory results than the former methods of testing by pressure alone, but 
owing to the fact that the cotton becomes compressed during rotation, 
thus changing the position of the vulcanite disk, the apparatus at 

• Report of chief inspector of the bureau for the safe transportation of explosives, February, 1909. 




10 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


times gives discordant results, and the figures from tests of any two 
explosives are not proportional to the relative tendency toward leakage 
of nitroglycerin under normal conditions. 

One of the authors designed a centrifuge attachment which is now 
being used with reliable results by the Bureau of Mines. This appa¬ 
ratus is shown in Plate I, A. Two samples of the explosive are placed 
in ordinary porcelain Gooch crucibles, without mat, the crucibles being 
held above two other nonp erf orated crucibles in the manner shown. 
A small amount of cotton is placed in each of the lower crucibles to 
receive the exuded nitroglycerin, and the loss by exudation is deter¬ 
mined by weighing the crucibles containing the explosive before and 
after rotation. The circle of rotation made by the bottom of the 
crucibles is 14 cm. in diameter, and the standard velocity of rotation is 
600 revolutions (30 turns of the handle) per minute. The usual test 
consists in placing 8 grams of explosive in each of the upper crucibles, 
and determining the loss in weight after rotating at the velocity of 
600 revolutions per minute for 5 minutes at a temperature of about 
20 ° C. If the explosive does not lose more than 5 per cent in weight 
it is considered to have satisfactory absorbing capacity, but if more 
than 5 per cent is lost its absorbent properties are considered defi¬ 
cient, and in the transportation or use of such an explosive there is 
considered to be liability of accident. 

TEST FOR STABILITY. 

Many tests have been proposed for determining the stability of 
explosives under the influence of heat, and much has been written in 
regard to the comparative accuracy of these different tests. This 
field is now being investigated by the bureau, and a special report 
thereon will be issued. At present all mining explosives examined 
by the bureau are tested for stability by means of the Abel heat test. 

ABEL TEST. 

The Abel stability test depends upon the fact that when potassium 
iodide is decomposed in the presence of starch, the iodine liberated 
reacts with the starch to form a colored body. The explosive to 
be tested is placed in a stoppered test tube and heated in a constant- 
temperature bath until the oxides of nitrogen liberated as de¬ 
composition products make a brownish color on a strip of potassium 
iodide starch paper suspended in the tube above the explosive. 
The stability of the explosive is judged by the time required for the 
production of a coloration of a standard intensity. The apparatus 
used in the Abel test is illustrated in Plate I, A. 

Two grams of explosive in its original condition, without prelimi¬ 
nary drying or preparation other than thorough mixing, is placed in 


BUREAU OF MINES BULLETIN 51 PLATE I 




♦ 


CENTRIFUGE FOR EXUDATION TEST OF DYNAMITE. B. APPARATUS FOR ABEL HEAT TEST. 








































« 






































































' 


















* * 







DYNAMITE. 


11 


a glass tube. The tube is of standard dimensions as follows: Length, 
K cm. (5^ inches); inside diameter, not less than 1.27 cm. inch); 
outside diameter, not more than 1.59 cm. (f inch); thickness of the 
glass, about 1.2 mm. inch). The tube is closed by a clean, 
tightly fitting cork stopper, through which passes a glass rod pro¬ 
vided with a platinum hook, fused into the lower end for holding the 
test paper. The test papers, in pieces about 2.5 cm. (1 inch) by 1.0 
cm. (f inch), are hung on the platinum hooks (forceps being used 
in handling) and the upper half of each strip of test paper is 
moistened with a solution of equal volumes of pure glycerin and 
water. 

The test paper used is potassium iodide starch paper, similar to 
that prepared by Eimer & Amend (Frankford Arsenal formula), or 
prepared by a standard method as described below. The heat-test 
bath is placed so that a good light—not direct sunlight—is trans¬ 
mitted through the test papers to the operator. The bath tempera¬ 
ture is maintained constant within 0.5° C. of the desired temperature 
(71° C.), the thermometer being so immersed that the bottom of the 
bulb is 2 \ inches below the top of the bath. 

All determinations are made in duplicate. The shorter time 
required to bring one of the two test papers to the prescribed tint 
determines the test of the explosive, except in case of wide variation 
in results, when two or more additional samples are tested. 

After each test the cork stopper of each tube is either discarded or 
carefully washed and dried and in any case is frequently renewed. 
The tube and the rod are carefully cleaned after each test, ether or 
other solvent being used to remove nitroglycerin, etc. They are 
then washed with water, and finally rinsed with distilled water. 
All the parts of the apparatus are dried in a steam oven at 100° C. 
The apparatus is at all times protected from laboratory fumes. 

The tube is inserted to a depth of 2J inches below the top of the 
bath, the water in the bath being within one-fourth inch of the top. 
The time of placing the tube in the bath is recorded, and the test is 
considered completed on the appearance of a brownish line at the 
lower edge of the moist portion of the paper, of the same intensity as the 
line on a standard-tint paper prepared as described below. It should 
be noted, however, that the brownish color on the test paper may at 
times be spread over a considerable portion of the paper, not forming 
a sharp, well-defined line. The operator should judge what would 
be equivalent to the standard tint over a width of one-half to 1 mm. 

Caramel standard tint 'paper *—The tint paper used as a standard 
color comparator for the test is made as follows: A solution of caramel 
in distilled water is prepared, of such concentration that when 
diluted to 100 times its volume (10 c. c. diluted to 1 liter) the tint of 


«30th Ann . Report H. M. Inspector of Explosives, 1905, p. 236. 



12 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


the solution equals that produced by the Nessler test on adding 2 c. c. 
of Nessler reagent to 100 c. c. of water containing 0.000075 gram of 
NH 3 , or 0.0002305 gram of NH 4 Cl. With a fine brush or pen dipped 
into this caramel solution fine lines are drawn on strips of filter paper 
(Schleicher and Schull, 597). These strips are cut to the size of the 
regular test papers (1 inch by f inch) so that the brown line crosses 
each piece near the middle of its length. The line should be J to 
1 mm. in width when dry. A piece of this standard tint paper 
should be placed in an empty tube beside those being tested, so that 
a comparison of color may be made. 

Preparation of test paper for Abel test .°—The paper used in pre¬ 
paring the test paper is Schleicher and SchulFs filter paper 597. 
This is cut in strips about 6 by 24 inches, and after being washed by 
immersing each strip in distilled water for a short time is hung up to 
dry overnight. The cords on which the paper is hung are clean 
and the room is free from fumes. The washed and dried paper is 
dipped in a solution prepared as follows: 

The best quality of potassium iodide obtainable is recrystallized 
three times from hot absolute alcohol, dried, and 1 gram dissolved 
in 8 ounces of distilled water. Cornstarch is well washed by decanta¬ 
tion with distilled water, dried at a low temperature, 3 grams rubbed 
into a paste with a little cold water, and poured into 8 ounces of 
boiling water in a flask. After being boiled gently for 10 minutes, 
the starch solution is cooled and mixed with the potassium iodide 
solution in a glass trough. 

Each strip of filter paper is immersed in the above-mentioned 
mixture for about 10 seconds and is then hung over a clean cord to 
dry. The dipping is done in a dim light and the paper left overnight 
to dry in a perfectly dark room. Every precaution is taken to 
insure freedom from contamination in preparing the materials and 
from laboratory fumes that might cause decomposition. When 
dry the paper is cut into pieces about f by 1 inch and is preserved 
in the dark in tight glass-stoppered bottles, the edges of the large 
strips being first trimmed off about one-fourth inch to remove por¬ 
tions that are sometimes slightly discolored. When properly pre¬ 
pared the finished paper is perfectly white, any discoloration indi¬ 
cating decomposition due to contamination. 

SAMPLING. 

The first step to be taken in the analysis of dynamite, as with any 
other material, is the careful preparation of a sample. Dynamite 
is offered in commerce in the form of cylindrical “sticks” or car¬ 
tridges, usually three-fourths inch to 1J inches in diameter and 8 


• Storm, C. G., Proc. 7th Inter. Congress Applied Chem. 1909; Jour. Ind. and Eng. Chem., vol. 1, 
1909, p. 802. 



DYNAMITE. 


13 


inches long. For special work dynamite is made in cartridges up to 
5 inches in diameter, but owing to restrictions in railroad trans¬ 
portation the length of cartridges of dynamite does not vary greatly, 
and cartridges over 8 inches long are unusual. 

A cartridge of dynamite consists of a c vering of paper, some¬ 
times waxed or parchmentized and often coated with paraffin, within 
which the dynamite is more or less tightly packed to give it the 
density desired. In the manufacture of dynamite the paper “shell” 
is first made, and is then packed with the explosive, after which the 
cartridge is sometimes “ redipped,” by which is meant that the 
cartridge is plunged into a bath of paraffin heated slightly above its 
melting point. The paraffin closes any openings in the wrapper and 
tends to make the cartridge waterproof. This operation of “redip- 
ping” is of interest in connection with the analysis of explosives 
chiefly because of the opportunity it affords for the entrance of 
paraffin into the explosive. When a paper shell is not perfectly 
made some paraffin is apt to find its way through the paper shell 
and be absorbed by the wood pulp. In sampling, care should 
always be taken to remove any paraffin that has found access through 
the ends of the cartridge, since obviously such paraffin is not to be 
considered as a normal constituent of the explosive, and care should 
also be taken in unwrapping the cartridge to prevent scales and 
flakes of paraffin from becoming mixed with the sample. 

The best method of sampling consists in opening the wrapper of 
each cartridge, spreading it out and cutting off from 3 to 5 cm. from 
each end of the roll of explosive thus exposed. These ends are 
rejected and the remainder carefully broken up to form a homoge¬ 
neous mass. When a sample representing a large quantity of pow¬ 
der—for example, a day’s output of a factory—is to be prepared, a 
number of cartridges are taken frim different mixings, the central 
portions of each cartridge are selected in the manner described, and 
these portions are finely broken up in a large porcelain evaporating 
dish or on a sheet of paraffined paper. The mass is carefully stirred 
with a clean spatula, or is rolled from side t ^ side upon the paraffined 
paper in the manner usually followed in preparing a sample of ore 
for assay. The stirring of the sample, or its rolling back and forth 
upon the paraffined paper, should occupy not less than five minutes, 
and the best results are obtained from such sampling when the 
explosive has been previously broken up to as fine a meal as possible 
by crumbling in the fingers or by gentle pressure with the spatula. 
A spatula suitable for this purpose is made of horn, or of wood 
saturated with paraffin so that it will not absorb nitroglycerin. 

From the large sample prepared as described a sample of 50 to 
100 grams is taken by selecting small portions from different parts 


14 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


of the mixed material, mixing these portions, and placing the mix¬ 
ture in the sample bottle. 

In preparing a sample of dynamite there are several factors that 
must be constantly borne in mind. If a thoroughly mixed sample 
is prepared and allowed to remain for some time in a sample bottle, 
a segregation occurs, and the lower portions of the material in the 
sample bottle become richer in nitroglycerin at the expense of the 
upper portions. In some dynamites, particularly one that contains 
almost as much nitroglycerin as its absorbent base can hold, this 
change occurs rapidly, and may make a difference of several per cent 
in a few days. The tendency to segregate is greatest in a tall bottle, 
and is favored by warmth, the action taking place several times as 
rapidly at 30° C. as at 20° C. An indication of the amount of segre¬ 
gation that is possible in dynamite is seen from the results of the fol¬ 
lowing experiment: 

A sample of dynamite was prepared by carefully breaking up and 
sampling two sticks of 60 per cent dynamite, about 300 grams being 
taken and placed in an ordinary bottle of 250 c. c. capacity (diameter 
about 6 cm., height about 14 cm.). At the time the sample was 
placed in the bottle the analysis of the material gave the following 
results: 

Analysis of 60 per cent dynamite. 

[W. C. Cope, analyst.] 

Moisture. 

Nitroglycerin. 

Potassium nitrate. 

Calcium carbonate. 

Wood pulp.. 


Per cent. 
. 1.40 

. 60.60 
. 18.64 
. 1.25 

. 18.11 


At the end of 10 days’ exposure to a temperature of 32° to 33° C. 
(average, 32.5° C.) samples were taken from the top, middle, and 
bottom of the material in the bottle, and the following results were 
obtained: 


Analyses of different parts of exposed sample of 60 per cent dynamite. 
[W. C. Cope, analyst.] 


Constituents. 

Sample 
from top. 

Sample 

from 

middle. 

Sample 

from 

bottom. 

Moisture.. 

Per cent. 
1.25 
59.46 
19.91 
1.37 
18.01 

Per cent. 
1.16 
60.55 
18.44 
1.33 
18.52 

Per cent. 

1 17 

Nitroplycerin. 

1.1/ 

Potassium nitrate. 

\jZ, oO 
17 AO 

Calcium carbonate.. 

1 / • 

1 OA 

Wood pulp. 

1. AO 

17 29 




















DYNAMITE. 15 

Another experiment was made to illustrate segregation in cartridges 
themselves. 

Whole cartridges of 40 per cent, 45 per cent, and 60 per cent dyna¬ 
mite were placed upright (on end) in a constant-temperature oven at 
40° for a period of four weeks, the cartridges being supported by 
small ware tripods within glass cylinders. Pinholes were punched in 
the bottom of the wrappers to allow the escape of any accumulation 
of nitroglycerin, but no such leakage occurred. 

At the end of four weeks samples were taken from the top and 
bottom of each cartridge, each sample representing about a 2-inch 
length of cartridge. The following results of analyses of these 
samples show the segregation of the nitroglycerin: 


Analyses of parts of samples of dynamite left standing on end for four weeks at 40° C. 
[J. H. Hunter, analyst.] 


Grade of dynamite, per cent. 

40 

45 

60 


Part of cartridge sampled. 

Nitroglycerin. 

Top. 

Per cent. 
38.20 
40.96 

Per cent. 
45.07 
47.98 

Per cent. 
57.27 
, 63.26 

Bottom. 



From the above described experiments it will be seen that the 
sampling of dynamite involves problems not met in the preparation 
of ore for assay. 

To determine any possible segregation due to nitroglycerin adhering 
to the dish in which a sample is mixed, 500 grams of dynamite was 
mixed in a large evaporating dish, and, when thorough mixing had 
been effected, was poured on a piece of paraffined paper. An analy¬ 
sis was then made of the large sample upon the paraffined paper, and 
the material adhering to the sides of the evaporating dish was 
removed by means of ether and analyzed. It was found that there 
was little difference between the composition of the two samples. It 
has been suggested that considerable changes in the moisture content 
of dynamite can occur during sampling, but this opinion does not seem 
correct. In the factory dynamite is usually mixed in an open mixer 
exposed to the atmosphere; consequently the percentage of moisture 
taken up or lost in the short length of time that the explosive is 
exposed to the air during sampling should be proportional only to 
the difference between the hygrometric condition of the air at the 
time the dynamite was made and that at the time it was sampled. 
To investigate this question further an experiment was made as 
follows: 

Two cartridges of one-half pound (226 grams) each were mixed 
together quickly, and with as little exposure to the air as possible. 
This original sample was found to contain 1.10 per cent moisture. 














16 


ANALYSIS OF BLACK POWDEE AND DYNAMITE. 


A 100-gram portion of this large sample was then mixed on a large 
watch glass for 10 minutes on a damp day when the humidity of 
the air as determined by hygrometer readings was 75 per cent. 
Another 100-gram portion was similarly treated on a diy day when 
the humidity was only 19 per cent. Determinations of moisture 
were then made on these two portions with the following results: 

Effect of exposure during sampling on moisture content of dynamite. 


Treatment of sample. 


Moisture. 


Without undue exposure. 

Stirred 10 minutes in moist atmosphere. 
Stirred 10 minutes in dry atmosphere... 


Per cent. 
1.10 
1.25 
1.10 


From these results it will be seen that the condition of the atmos¬ 
phere has little effect on the moisture content of a sample when the 
sampling is done with reasonable dispatch and when atmospheric 
conditions are not abnormal. 

CHEMICAL EXAMINATION. 

QUALITATIVE EXAMINATION. 

When no information is available as to the class to which an explo¬ 
sive to be analyzed belongs, a complete qualitative analysis is desir¬ 
able, so that the proper methods of quantitative separation may be 
followed. 

For the qualitative examination of a dynamite of any type a sam¬ 
ple of 20 to 25 grams is most convenient. The sample is placed in a 
1 -inch test tube, which is then filled to about two-thirds of its depth 
with ether, stoppered, and well shaken. The ether is decanted 
through a filter paper and fresh ether is added to the tube. This 
treatment is repeated several times, and the residue is finally trans¬ 
ferred to the filter and again washed with fresh ether. After the 
ether is drained off, the filter paper with its contents is removed 
from the funnel, spread out on a glass plate, and placed in a drying 
oven for a short time until nearly all the ether has evaporated. The 
dry residue is transferred from the filter back to the test tube, and is 
then ready for treatment with cold water, to remove the water- 
soluble constituents. 

The ether solution is evaporated on a steam bath or electric heater 
at a low temperature until all odor of ether has disappeared. If 
the evaporation has caused the deposition of water in the beaker 
with the extract, this water is removed by placing the beaker in a 
vacuum desiccator for an hour or two. The presence of nitro¬ 
glycerin is readily noted, the characteristic oily appearance of 









DYNAMITE. 


17 


nitroglycerin and its viscosity serving to identify it. A convenient 
chemical test is to mix a drop of the heavy liquid, supposed to be 
nitroglycerin, with 1 or 2 c. c. of concentrated sulphuric acid in a 
test tube, and then to add about 1 c. c. of mercury. No stopper of 
any sort should be placed in the tube, but it should be shaken quickly 
from side to side so as to cause intimate contact of the mercury with 
the acid mixture. For 1 or 2 minutes little effect will be observed, 
but after a short time there will be noted, if the material under 
examination is nitroglycerin, the evolution of bubbles of gas from 
the liquid at the point where it comes in contact with the mercury, 
and the characteristic smell of nitrogen oxides will be noted. The 
nitric oxide (NO) produced is colorless, but upon coming in con¬ 
tact with the air it turns red or reddish-brown, forming nitrogen 
peroxide (N0 2 ). A simpler test for the presence of nitroglycerin, 
though by no means so satisfactory as the one just described, con¬ 
sists in taking up a small amount of the liquid in a capillary glass 
tube, and holding it cautiously in a flame. A strong detonation 
will result if the liquid is nitroglycerin. It is of course evident that 
there should be not more than a tiny fraction of a drop of nitro¬ 
glycerin used in such a test, the best results being obtained when 
a very thin and small capillary is used, containing not more than 
0.01 of a drop of the liquid tested. 

If sulphur is present in the ether extract it will crystalize in needles 
or small granular masses in the residue upon the evaporation of the 
ether. The crystals of sulphur can be removed, washed free from 
nitroglycerin with a little acetic acid (70 per cent or glacial), after 
which they should be washed with water, dried, and heated over a 
flame. The odor of sulphur dioxide (S0 2 ) will identify the crystals 
as sulphur. Trinitrotoluene appears as long yellowish needles, 
which may be recrystallized from alcohol and identified by their 
melting point (80° C.), or by the color test with potassium or sodium 
hydroxide.® This color test is valuable as a means of identifying 
many of the nitrosubstitution products, although in a mixture the 
color produced by one* constituent may completely hide the others. 
For example, the wine-red color obtained from trinitrotoluene may 
prevent the identification of other nitrocompounds that maybe 
present. The test may be made directly on a portion of the ether 
extract, since the presence of nitroglycerin does not in any way 
interfere. The sample under examination is dissolved in 2 to 3 c. c. 
of acetone or methyl alcohol, and a few drops of 10 per cent potas¬ 
sium or sodium hydroxide added. The characteristic colors pro¬ 
duced by various nitrosubstitution compounds are shown in the 
table following. 

a Gody, L., Traite tli^orique et pratique des matures explosives, 1907, p. 599. 

67709°—Bull. 51—13-2 



18 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


Color reactions of nitrosubstitution products with alkalies. 


Substance. 


Form. 


Color of solution. 


Result of addition of alkaline 
solution. 


Mononitrobenzene. 
Dinitrobenzene.... 


Liquid. Colorless- 

Crystal. Faint yellow 


Trinitrobenzene. 

Mononitrotoluene (ortho). 
Mononitrotoluene (meta). 
Mononitrotoluene (para).. 
Dinitrotoluene.. 


_do.. 

Liquid. 
Crystal. 

_do.. 

-do.. 


Colorless to 
yellow. 

-do. 

_do. 

_do. 

_do....... 


pale 


Trinitrotoluene. 

Mononitronaphthalene. 
Dinitronaphthalene.... 
Trinitronaphthalene... 
Tetranitronaphthalene. 
Picric acid. 


do. 

.do. 

.do. 

.do. 

do. 

.do. 


....do. 

-do. 

Pale yellow... 

_do. 

_do. 

Golden-yellow. 


No effect. 

Purple-rose, turning to deep 
claret. 

Rich purple-brown. 

No effect. 

Slight yellow. 

No effect. 

Gradual evolution of azure 
blue on standing. 

Deep wine-red brown. 

No effect. 

Reddish-yellow. 

Bright scarlet. 
Reddish-yellow. 

Precipitate of crystals of 
potassium picrate (orange). 


Rosin, vaseline, paraffin, oils, etc., are found in the extract, after 
evaporation of the ether, as a dark-colored, greasy mass on the sur¬ 
face of the nitroglycerin or adhering to the walls of the beaker. 
Small amounts of resins and oils are generally found in the extracts 
from ordinary dynamite, these being normal constituents of the 
wood pulp, flour, or similar absorbents. The amount of such mate¬ 
rials present is usually too small to be of any importance, and where 
only small traces are found they may best be disregarded. If it is 
desired to identify such materials the method for quantitative 
determination described later may be followed. 

The water solution is examined for sodium, potassium, ammonium, 
zinc, the nitrate ion, etc. The qualitative and quantitative tests for 
these elements are discussed fully in all textbooks of analysis, and 
accordingly need not Be repeated here. In ordinary qualitative 
work the writers have found the ring test for nitrates, with the use 
of the nitrometer in any doubtful case, to be most satisfactory; 
potassium and sodium are best identified by the color they impart 
to the flame of the Bunsen burner, viewed through at least two 
thicknesses of cobalt glass. The best test for ammonium is the 
evolution of ammonia by reaction with calcium oxide or sodium 
hydroxide. Small quantities of iron, aluminum, chlorides, sul¬ 
phates, etc., are generally found in all dynamites as impurities from 
the raw materials used. 

The residue insoluble in water is treated with cold dilute hydro¬ 
chloric acid; effervescence, if noted, is an indication of the presence 
of a carbonate, and the usual tests are then made for C0 2 . The acid 
extract after filtering is tested for calcium, magnesium, zinc, etc., 
whose carbonates or oxides may have been present in the powder as 
antacids. 

The residue insoluble in water and dilute acid is best examined 
under the microscope, a magnification of 30 to 50 diameters being 














































DYNAMITE. 


19 


most convenient for all ordinary work. The identification of starch, 
cereal products, wood pulp, sawdust, kieselguhr, nitrocellulose, etc., is 
discussed in another part of this paper. 

A starch test is readily made by heating a portion of the mate¬ 
rial to boiling with dilute acid, cooling and adding a drop of iodine 
solution, this operation producing an intense blue coloration if 
starch is present. 

DETERMINATION OF MOISTURE. 

The moisture present in dynamite may be determined in the fol¬ 
lowing ways: 

(a) By drying in a desiccator over sulphuric acid, calcium chloride, 
or other suitable drying agent without vacuum. 

(b) By drying in a desiccator with vacuum. 

(c) By passing dry air through the sample. 

These methods have been carefully studied, and the first method, 
drying over sulphuric acid in a desiccator, has been found to have 
the widest application, and to be the most desirable in the analysis 
of explosives. In the determination of moisture in a sample of 
dynamite a number of important factors should be considered in 
order that accurate results may be obtained. The weight of the 
sample, the manner in which the sample is spread upon the watch 
glass, the size and type of desiccator, the exposed area of the desic¬ 
cating agent, as well as its quantity and condition and the tem¬ 
perature at which the desiccation is carried out—all have an important 
bearing on the loss of weight resulting from desiccation, and unless 
care is taken moisture determinations made at different times on the 
same sample of dynamite will frequently give somewhat different 
results, owing to the slight variations in some of the above-named 
factors. 

Preliminary studies were made to determine the amount of dyna¬ 
mite that is most suitable for the determination of moisture, and the 
thickness with which the sample should be spread upon the watch 
glass. The results of these tests showed that a sample of less than 
2 grams of explosive is unsatisfactory, owing to the errors intro¬ 
duced, for example, by particles of material being carried away by 
the air during weighing, or upon opening the desiccator. When 
more than 2 grams of sample was taken the length of time required 
to effect thorough drying was unduly long; and consequently 2 
grams of material, spread evenly on the concave surface of a 3-inch 
watch glass, was deemed the best amount for the determination. 
When only one or two analyses have to be run at a time, it is con¬ 
venient to use a separate 5 or 6 inch desiccator for each sample, the 
bottom of the desiccator containing about 50 to 75 c. c. of concen¬ 
trated sulphuric acid, and the watch glass being held by a triangle 


20 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


at a convenient and suitable distance above the acid. Objections 
have been raised a to the use of sulphuric acid as a desiccating agent 
in the determination of moisture in dynamite. The experience of 
the writers has shown these objections to be without grounds. 

When a number of determinations are being made at the same 
time it is convenient to use larger desiccators, and the 10-inch size has 
been found to be satisfactory, five watch glasses being conveniently 
held at one time in such a desiccator. 

IN ORDINARY DESICCATORS. 

The period required for desiccation of a sample of dynamite in 
an ordinary desiccator is about 3 days or 72 hours. The first 12 
hours within the desiccator reduces the moisture content to a very 
low percentage, but it has been found desirable to allow all samples 
to remain a further period of 60 hours, as the remainder of the moisture 
is slowly removed. The loss in weight, at the end of three days, 
of the 2-gram sample of dynamite on the watch glass is taken as 
moisture. After three days’ drying, small amounts of moisture are 
still present, particularly in the wood pulp, but drying longer than 
three days has not been found desirable in ordinary analytical work. 
By long-continued desiccation, over either calcium chloride or 
sulphuric acid, a further gradual loss occurs which is evidently due 
to volatilization of nitroglycerin, and the amount of this loss varies 
with the temperature. Taking the loss of weight at the end of three 
days as representing moisture has been found to give uniform results 
in the case of dynamites of most varied composition, and has 
been adopted in the bureau’s laboratory as a standard method, 
although it is impossible to say that at the end of any definite time 
all moisture has been removed from the sample and that further loss 
is due to volatilization of nitroglycerin. 

Care should always be taken to spread the sample in a thin and 
uniform layer over nearly the entire surface of the watch glass, and 
the spreading should be done as quickly as possible to prevent 
undue exposure to the atmosphere. Experiments in which different 
sizes of desiccators (4-inch to 9-inch) were used showed that the rate 
of drying increased as the ratio of acid surface to powder surface 
increased, but that in three days the loss in all cases was practically 
the same. The effect of such variation is shown in the following 
table of results of tests of explosives containing amounts of moisture 
greater than that in ordinary dynamite. The table also jshows a 
comparison between the efficiencies of two types of desiccators— 
the Scheibler, or ordinary type, which contains the acid in the bot- 

a Gody, L., Traite theorique et pratique des matures explosives, 1907, p. 382; Guttmann, O., Schiess- 
und Sprengmittel, 1900, p. 162. 




DYNAMITE. 


21 


tom below the sample, and the Hempel type in which the acid is 
contained in the top or cover, above the sample. With an acid sur¬ 
face about 75 per cent as great as in the ordinary type the Hempel 
desiccator appears to be slightly more efficient than the Scheibler. 


Results of moisture determinations showing effect of variation in acid surface and 
in type of desiccator. 



Scheibler. 

Scheibler. 

Hempel. 


Size of desiccator.. 

4-inch. 

9-inch. 

6-inch. 


nf nnifi surface ( approximated. 

/ 7 square 
\ inches. 

50 square 
inches. 

38 square 
inches. 


Name of explosive. 

Time of 
drying. 

Moisture content determined by 
loss of weight. 


Hours. 

} 6 

12 

\ 24 

1 8 

J 52 

I 48 

l 72 

Per cent. 
5.73 
8.82 
10.06 
10.52 
10. 66 
1.89 
4.09 
5.34 

5.49 

5.50 

Per cent. 

9.84 
10.11 
10.33 
10.63 
10.68 

Per cent. 
9.97 
10.29 
10.43 
10.65 
10.79 
3.18 
4.88 
5.51 
5.60 
5.63 

Explosive A<»....j 

Explosive B ® . 


5.50 


5.59 


a Arbitrary designation of sample. 


The quantity of acid used in the desiccator must also be considered, 
because the dilution of the acid by the absorbed moisture is dependent 
upon the amount of acid present. In general, the acid contained in a 
desiccator does not require frequent renewal, and when from 50 to 75 
c. c. of concentrated sulphuric acid (H 2 S0 4 ) is used in the desiccator 
the renewal of this material once each month or once every two 
months is all that is necessary. 

The following experiment illustrates the effect of dilution of the 
sulphuric acid by the absorption of considerable moisture from pow¬ 
der samples. Two samples of the same dynamite were desiccated in 
similar desiccators, one containing 75 c. c. of 96 per cent sulphuric 
acid, the other the same volume of 90 per cent sulphuric acid. In 
three days the losses of moisture were 1.10 per cent and 1.02 per 
cent,, respectively, and in five days 1.17 per cent and 1.05 per cent, 
respectively. In order that 75 c. c. of 96 per cent acid could become 
diluted to 90 per cent by the absorption of moisture from dynamite 
samples, it would be necessary that all of the moisture from about 
460 2-gram samples of dynamite, each containing 1 per cent mois¬ 
ture, be absorbed by the acid. It is therefore obvious that the acid 
in the desiccators will not become diluted enough in one or two 
months to lose appreciably its affinity for moisture. 























22 ANALYSIS OF BLACK POWDER AND DYNAMITE. 

The effect of temperature on the moisture determination is shown 
in the following experiments, made with a 60 per cent dynamite. 
Three determinations of moisture were made on the same sample at 
widely different temperatures. Two grams of the sample in one 
desiccator were placed in an incubator, the temperature of which, 
by means of a thermostat, was regulated to a range of 36° to 38° C. 
(96.8° to 100.4° F.). A second desiccator containing another 2 
grams of the sample was placed out of doors, the temperature varying 
during the experiment from —23° to 2° C. ( — 9.4° to 35.6° F.). A 
third desiccator containing a third 2-gram portion of the sample was 
left at room temperature, which varied from 17° to 25° C. (63° to 77° 
F.). In each of these experiments the 2-gram parts of the sample 
were spread upon 3-inch watch glasses, each watch glass being placed 
in a separate 4-inch desiccator containing 75 c. c. of fresh sulphuric 
acid. The results are tabulated below: 


Results of tests to determine the moisture content of dynamite, showing the influence of 

temperature. 


1 

2 

3 

4 

5 

6 

Sample 

No. 

Temperature. 

Days. 

exposed. 

Loss of 
weight 
on des¬ 
iccation. 

Ether extract. 

Nitroglycerin in 
ether extract.** 

Maxi¬ 

mum. 

Mini¬ 

mum. 

Mean. 

By loss. 

By direct 
weight. 


°C. 

°C. 

°C. 


Per cent. 

Grams. 

Grams. 

Grams. 

Per cent. 





[ 3 

1.00 









6 

1.06 





1 

25 

17 

21 

\ 7 

1.06 









10 

1.19 









l 13 

1.31 

1.2158 

1.2126 

1.2051 

60.26 





f 3 

1.69 









6 

2.49 





2 

38 

36 

37 

\ 7 

2.74 









10 

3.54 









l 13 

4.12 

1.1563 

1.1522 

1.1397 

56.99 


-7 

-16 

1 

l 3 

0. CO 






-3 

-23 

1 

6 






3 

0 

-14 

( ~ 9 

{ 7 

0.72 






2 

- 9 

J 

10 

0.67 






20 

18 

19 

l 13 

1.03 

1.2243 

1.2220 

1.2114 

60.57 


a Determined by nitrometer. 


After the weighings had been made on the thirteenth day the 
samples were carefully transferred to Gooch crucibles, and extracted 
with ether in a Wiley extractor." The crucibles were then dried at 100° 
C., and the losses in weight determined, which are given in column 5. 
The nitroglycerin in each sample of ether extract was then deter¬ 
mined by the nitrometer after the ether had been evaporated (see 
p. 35). The results shown under “loss of weight by desiccation” 
(column 4) indicate the pronounced influence which temperature has 
on the determination of moisture. In the case of sample 2 most of 
the moisture was probably lost within the first 24 hours, the further 


• For the method used in the extraction see p. 30. 





















DYNAMITE. 


23 


loss being entirely due to the evaporation of nitroglycerin. In the 
case of the sample 3 the weight first taken, at the end of three days, 
showed a loss of only 0.60 per cent. As previous experiments had 
shown that this amount of moisture can be removed from 60 per 
cent dynamite by about two hours' desiccation, it is probable that 
the loss noted during the first three days resulted during the first 
two hours' desiccation, before the sample became frozen. Practi¬ 
cally no further loss occurred in this sample up to 10 days, and the loss 
which occurred between the tenth and thirteenth day was due to the 
fact that the sample had thawed. As the temperature in the labora¬ 
tory frequently reaches 35° C. or more during the summer, it is 
evident that abnormally high results sometimes obtained during 



DAYS 


Figure 1.—Influence of temperature on determination of moisture in 60 per cent dynamite by desiccation 
over sulphuric acid. Temperature (mean): No. 1,21° C.; No. 2,37° C.; No. 3, —9° C. 

warm days of summer may be in error to a considerable extent, being 
only in part due to loss of moisture and in part to volatilization of 
nitroglycerin. Since incorrect results are obtained when moisture 
is determined at a low temperature, no determinations of moisture 
should be made at a temperature sufficiently low to cause the sample 
to freeze. In order that perfectly uniform results may be obtained 
with samples of dynamite, the temperature of the room in which the 
desiccation is carried out should be practically constant at 20° C. 
This is a normal working temperature, and when moisture deter¬ 
minations are made at temperatures materially above or below it, 
allowance should be made for the influence of the abnormal tempera¬ 
ture. The results given in the table on p. 22 are shown in the form 
of curves in figure 1. The curve for sample 3 represents the results 















































































24 


ANALYSIS OF BLACK POWDEE AND DYNAMITE. 


of the first 10 days’ exposure, during which period the sample 
remained frozen. 

In the determination of moisture by the bureau’s explosives labo¬ 
ratory, sulphuric acid has been accepted as the standard desiccating 
agent. As many chemists prefer to use calcium chloride, the following 
experiment is of interest, as showing the difference in efficiency of 
these two desiccating agents. Six 2-gram samples of 60 per cent 
dynamite were weighed from a large, well-mixed sample. Three of 
these samples were desiccated over calcium chloride and three over 
sulphuric acid. An individual 6-inch Scheibler desiccator was used 
for each sample. Weighings made at intervals showed the loss of 
moisture as follows: 

Results of desiccation of 60 per cent dynamite over calcium chloride and over sul¬ 
phuric add , at room temperature. 


Time. 

Designa¬ 
tion of 
sample. 

Loss of 
weight, over 
calcium 
chloride. 

Designa¬ 
tion of 
sample. 

Loss of 
weight over 
sulphuric 
acid. 

Days. 


Per cent. 


Per cent. 

A 

A 

0.50 

C 

0.64 

i 

A 

.59 

C 

.73 

1 

A 

62 

c 

.79 

B 

.66 

D 

.87 

1 

A 

.67 

C 

.84 

2 

B 

.77 

D 

.94 

3 

A 

.77 

C 

.96 

3 

B 

.80 

D 

.97 

3 

E 

.84 

F 

1.02 

5 

A 

.84 

C 

1.01 

5 

B 

.87 

D 

1.01 

5 

E 

.91 

F 

1.07 

6 

A 

.84 

C 

1.02 

6 

A 

.87 

D 

1.05 

6 

E 

.93 

F 

1.10 

10 

A 

.95 

C 

1.11 

10 

B 

1.00 

D 

1.17 

10 

E 

1.00 

F 

1.20 

13 

A 

1.07 

C 

1.23 

13 

B 

1.10 

D 

1.32 

13 

E 

1.15 

F 

1.36 

16 

A 

1.16 

C 

1.33 

16 

B 

1.13 

D 

1.46 

16 

E 

1.25 

F 

1.48 

19 

E 

1.25 

F 

1.53 

20 

E 

1.37 

F 

1.60 

34 

E 

1.72 

F 

2.01 

50 

E 

2.22 

F 

2.55 

75 

E 

2.82 

F 

3.35 

111 

E 

3.67 

F 

4.55 

183 

E 

5. 77 

F 

7.55 

237 

E 

6.85 

F 

9.20 


These results, plotted in the form of curves for the two samples 
E and F, upon which desiccation was continued the longest, are 
shown in figure 2. 

The fact that nitroglycerin is more or less volatile even at ordinary 
temperatures is recognized by most explosives chemists, and in 
some laboratories an endeavor is made to avoid loss of nitrogly¬ 
cerin during desiccation by keeping the atmosphere within the 
desiccator saturated with nitroglycerin vapors. This is done by 
placing in the desiccator, together with the sample of dynamite on 








DYNAMITE. 


25 


which moisture is to be determined, a quantity of nitroglycerin on 
a watch glass, it being assumed that the evaporation of this nitro¬ 
glycerin will saturate the atmosphere in the desiccator and minimize 
the loss of nitroglycerin from the sample of dynamite. 

To test the value of such method the following experiments were 
made: Four samples (2 grams each) of the same 60 per cent dyna- 



DAYS 

/ 

Figure 2.—Results of desiccation of 60 per cent dynamite over calcium chloride (E) and over sulphuric 

acid (F) at room temperature. 

mite used above were spread on 3-inch watch glasses and placed in 
separate desiccators. Directly underneath each of the watch glasses 
was placed a watch glass containing a layer of fine dry sand saturated 
with nitroglycerin. Two of the desiccators contained sulphuric acid 
and two calcium chloride. Weighings of the dynamite samples at 
intervals showed losses of weight as follows: 

Results of desiccation of 60 per cent dynamite over calcium chloride and over sulphuric 
acid in an atmosphere saturated with nitroglycerin vapors. 


Designa- 
tion of 
sample. 

Desiccation over cal¬ 
cium chloride. 

Designa¬ 
tion of 
sample. 

Desiccation over sul¬ 
phuric acid. 

Time. 

Loss of 
weight. 

Time. 

Loss of 
weight. 

A 

Days. 

3 

Per cent. 

0.77 

c 

Days. 

3 

Per cent. 

B 

3 

.80 

D 

3 

0.92 

A 

6 

.93 

C 

6 

1.10 

B 

6 

.97 

D 

6 

1.12 

A 

10 

1.02 

C 

10 

1.13 

B 

10 

1.00 

D 

10 

1.15 

A 

13 

1.15 

c 

13 

1.20 

B 

13 

1.17 

D 

13 

1.25 

A 

19 

1.25 

C 

19 

1.31 

B 

19 

1.35 

D 

19 

1.40 

























































































26 ANALYSIS OF BLACK POWDER AND DYNAMITE. 

Comparing these results with those of the table on page 24, it will 
be noted that the placing of an additional amount of nitroglycerin 
in the desiccator with the sample of dynamite has practically no 
effect on the amount of nitroglycerin lost from the sample. 

The fact that nitroglycerin volatilizes in the desiccator in the 
presence of either sulphuric acid or calcium chloride suggested the 
carrying out of experiments to determine whether a sample of dyna¬ 
mite that had been desiccated for a sufficient time to lose all of its 
moisture would continue to lose weight in an empty desiccator (with¬ 
out any desiccating agent present). 

Two 2-gram samples of 60 per cent dynamite were dried for three 
days on watch glasses over sulphuric acid, and then immediately 



Figure 3.—Result of exposure of dry 60 per cent dynamite in a desiccator at 33° to 35° C. without desic 

eating agent. 

placed in clean desiccators without any drying agent. One of these 
was kept at room temperature (17° to 22° C.), the other in a constant- 
temperature incubator oven at a temperature of 33° to 35° C. 
Weighings made at intervals showed a continued steady loss from 
the sample at 33° to 35°, whereas the sample exposed to room tem¬ 
perature gained in weight at first, then steadily lost until at the end 
of about 40 days it had attained its original weight. In the table 
below the percentage of loss or gain in weight recorded represents 
the variation from the dry weight of the samples after having been 
desiccated three days. 



































































DYNAMITE. 27 

Change in weight of dried samples of 60 per cent dynamite in desiccators containing no 

desiccating agent. 



Change in weight. 

Time in 
desiccator. 

Sample A (17°-22° C.). 

Sample B 
(33°-35° C.). 


Gain. 

Loss. 

Loss. 

Days. 

Per cent. 

Per cent. 

Per cent. 

4 

0.36 


0.13 

7 

.35 


.46 

10 

.30 


.80 

13 

.25 


1.10 

16 

.20 


1.40 

20 

.20 


1.75 

41 


0.05 

3.40 

77 


.67 

5.35 

202 


2.63 

9.33 


It is often desirable to make a weighing at a shorter interval than 
72 hours, and to obtain an approximation of the true moisture by 
calculation. An extended series of tests was made to determine 
what factor could be safely used, in conjunction with a weight 
taken at the end of 24 hours, to give the same result as would be 
obtained by desiccation for a period of 72 hours. It was found that 
the influence of the temperature of the room in which the desiccator 
was kept was so marked, and the difference in effect between differ¬ 
ent desiccating agents, a was such as to make this method uncertain. 
At the best only an approximation can be obtained, but when time 
is more important than accuracy a rough approximation to the true 
moisture content of ordinary dynamite can be obtained by consid¬ 
ering the loss in weight over sulphuric acid in 24 hours to be 90 per 
cent of the total moisture. In other words, the loss of weight in 24 
hours’ desiccation multiplied by the factor 1.11 will be an approxi¬ 
mation to the true moisture content. When large amounts of mois¬ 
ture are present, as in certain types of coal-mining explosives con¬ 
taining water added as a constituent of the explosive, it is not 
advisable to attempt the use of such a factor. In such cases the 
loss of weight on desiccating three days is considered as the total 
moisture. 

IN VACUUM DESICCATORS. 

The evaporation of water is much more rapid at reduced pressure 
than under atmospheric pressure, and therefore the determination 
of moisture may be made in a shorter tune with the use of a vacuum 
than when atmospheric pressure prevails within the desiccator. 
If nitroglycerin were perfectly nonvolatile, desiccation in a vacuum 
would probably be sufficiently reliable for use as a standard method. 


a See table on p. 24. 





















28 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


The following table shows the results obtained when samples of the 
same dynamite were exposed in desiccators of similar size and shape 
that contained the same desiccating agent, in one case a vacuum 
being used and in the other case the air within the desiccator being 
at the pressure of the air in the room. 

Results of desiccating tests with and without vacuum in the desiccator. 


Time dried. 

Sample in 
ordinary- 
desiccator. 

Sample in 
vacuum 
desiccator. 

Loss of moisture in 24 hours.. 

Per cent. 
5.34 
5.49 
5.68 

Per cent. 
5.42 
5.63 
5.80 

Loss of moisture in 48 hours. 

Loss of moisture in 72 hours. 



With the ordinary type of desiccator, containing acid in the bottom, 
moisture is removed from the sample much more rapidly with a 
vacuum than without, other conditions being equal. For example, 
in a 4-inch desiccator, with 7 square inches of acid surface on which 
the pressure was that of the atmosphere, the loss of moisture from 
a powder sample containing about 11 per cent of water was only 54 
per cent of the total in 6 hours, 83 per cent in 12 hours, and 94 per 
cent in 24 hours. In a slightly larger desiccator of the same type, 
with 12 square inches of acid surface, above which there was a 
vacuum, the loss in 6 hours was 91 per cent, in 12 hours 95 per 
cent, and in 24 hours 96.5 per cent. In both samples a practically 
constant value was obtained in 3 days. 

In the case of the Ilempel desiccator, containing acid above the 
explosive sample, the rate of loss of moisture is nearly the same with 
or without vacuunp 

In general it may be stated that any type of vacuum desiccator 
will remove in 12 hours practically all the moisture from dynamites 
and even from permissible explosives containing as much as 10 to 
12 per cent of water, the result thus obtained being about the same 
as that given by 3 days’ desiccation without vacuum. 

Vacuum desiccation for a longer time than 12 hours will cause a 
further slight loss, which is probably for the most part due to vola¬ 
tilization of nitroglycerin. 

IN A DRY-AIR CURRENT. 

When a current of air previously dried by being passed through a 
calcium chloride tube, or through sulphuric acid, is passed through 
a mass of dynamite in a suitable sample tube, the dynamite gives up 
its moisture to the dry air. Drying may be very quickly effected in 
this manner, because of the fact that the dry air comes into intimate 
contact with all portions of the explosive, but the method has the 










DYNAMITE. 


29 


serious defect of being inaccurate, owing to the volatility of nitro¬ 
glycerin. 

In desiccation by means of dry air, a drying tube of the form 
shown in figure 4 is usually employed. Sometimes several of these 
tubes are connected together in a train. The dry air is always intro¬ 
duced at the bottom, so that it may rise through the explosive, and 
a weighed sample of about 15 grams is generally taken for the deter¬ 
mination. 

Several tests were made to determine the accuracy of this method 
of drying samples of dynamite. A current of air dried by passing 
through sulphuric acid was passed through a sample of dynamite 
which had been found, by desiccation for three days over sulphuric 
acid, to contain 5.68 per cent of moisture. Weighings at intervals 
showed loss of weight as follows. 

Loss of weight of dynamite in a current of dry air. 


Time 

dried. 

Loss of 
weight. 

Hours. 

Per cent. 

2 

1.47 

6 

4.29 

12 

5.20 

24 

5.50 

48 

5.70 

60 

5.80 

72 

5.86 


The table shows that at the end of 48 hours there had been a loss 
in weight approximately corresponding to the percentage of moisture 
found in the explosive by the standard method. The constant loss 
after that point represents volatilization of nitroglycerin, although 
it is of course to be noted that the loss of nitroglycerin was continu¬ 
ous, nitroglycerin being removed from the time the air first began to 
pass through the sample. How inaccurate this method is may be 
readily understood when one remembers that nitroglycerin can be 
completely volatilized by bubbling dry air through it for a sufficient 
length of time, and that accordingly any sample of dynamite would 
probably reach an ultimate value in which the loss in weight would 
correspond to the amount of moisture plus the amount of nitroglyc¬ 
erin present in the sample. 

SUMMARY. 

The most satisfactory method for the determination of moisture 
consists in using a 3-inch watch glass containing an evenly distrib¬ 
uted 2-gram sample, the watch glass and sample being placed in a 
desiccator containing sulphuric acid, and being weighed at the expira¬ 
tion of 72 hours. Care should be taken that the temperature does not 
vary widely from a mean of 20° C. An approximation of the true 





30 ANALYSIS OF BLACK POWDER AND DYNAMITE. 

moisture content of the sample of explosive may be obtained by des¬ 
iccating in the manner just described for a period of 24 hours, and 
multiplying the loss in weight thus found by the factor 1.111, or the 
loss in a vacuum desiccator for 24 hours may be taken without fur¬ 
ther calculation as an approximation to the true moisture content 
as determined by standard methods. 

EXTRACTION WITH ETHER. 

Extraction with ether removes from dynamite not only nitro¬ 
glycerin, but also any resins or sulphur that may be present. Aside 

from resin intentionally admixed 
there is always some resin present 
in the wood pulp. In addition to 
these constituents, in dynamite 
small amounts of oil are sometimes 
found,having been introduced from 
mixing machines or packing ma¬ 
chines. When flour, corn meal, or 
other grain or cereal products are 
present as constituents of explo¬ 
sives a small amount of oil from 
such materials is also found in the 
ether extract. Nitrotoluenes, par¬ 
affin, vaseline, etc., are not normal 
constituents of ordinary dynamite, 
and the determination of these substances is discussed under the 
type of explosive in which they occur as characteristic components, 
but it is to be noted that were any of these materials present in 
dynamite they would be found in the ether extract. 

REFLUX-CONDENSER METHOD. 

A sample of from 6 to 10 grams of the explosive is weighed in either 
a porcelain Gooch crucible with asbestos mat or a porous alundum a 
crucible of about 25 c. c. capacity. WEen a Gooch crucible is used 
the mat should be light, but should be perfectly coherent. Such a mat 
is prepared in the bureau’s explosives laboratory as follows: Five 
grams of short-fiber asbestos, in the form of short shreds, free from 
hard lumps, is added to 1 liter of water. Wlien used the mixture is 
well shaken and about 10 c. c., an amount sufficient to fill the crucible 
to about two-thirds of its depth, is poured into the crucible. Suc¬ 
tion is applied, and a smooth and perfect mat is almost invariably 
produced. The crucible and mat are then carefully dried for some 
hours at 100°, weighed, and placed in a desiccator. For extracting 
with ether, the form of apparatus found most satisfactory is the 



a A trade name for artificially prepared porous aluminum oxide. 









DYNAMITE. 


31 


Wiley extractor, as shown in Plate II, A. The crucible is supported 
on a small hanger made by twisting No. 18 copper wire into suitable 
shape. 

In performing an extraction the crucible, with its weighed sample 
of explosive, is placed in the hanger, and about 35 c. c. of U. S. P. ether 
(96 per cent) is poured in several portions through the sample into the 
glass extraction tube. Water is continuously circulated through the 
cooling coils of the condenser. The ether is boiled by means of an 
electric heater or a vessel of hot water in which the lower part of the 
tube is immersed. The ether vapor condenses on the surface of the 
metal condenser, the condensed ether dropping into the crucible and 
percolating through the sample of explosive. The temperature is 
regulated so that the sample will be kept covered with ether without 
any overflow. 

When a vessel of hot water is used for heating the tube, the ether 
partly drains out of the crucible during a change of water, but is at 
once replaced by a fresh supply. This intermittent action probably 
accomplishes a more efficient extraction than is obtained by keeping 
the sample continuously covered with ether. The extraction with 
ether is continued for about three-fourths of an hour for most explo¬ 
sives. This period is usually somewhat longer than is necessary to 
remove all of the nitroglycerin, but it is desirable to carry on the 
extraction long enough to insure the complete removal of material 
soluble in ether, so as to avoid testing for completeness of extraction. 
If for any reason a shorter time for extraction is desirable, the extrac¬ 
tion is continued for the time desired, after which a small additional 
amount of ether is put into the apparatus, and the ether passing 
through the crucible is evaporated in a watch glass and an examina¬ 
tion made for residue. If residue is found, complete extraction has 
obviously not been accomplished. 

The crucible containing the portion of the explosive insoluble in 
ether is placed in a drying oven heated to about 100° C. This should 
be done promptly, since the evaporation of the ether with which 
the contents of the crucible are saturated lowers the temperature of 
the crucible sufficiently to cause the precipitation of considerable 
moisture upon the crucible and its contents, and such a precipita¬ 
tion is undesirable as it necessitates longer drying. Although no 
loss or inaccuracy in analysis is liable to result from the constituents 
of the explosives becoming wet at this stage, yet for uniform results 
in drying it is usually best to transfer the crucible directly from the 
Wiley extractor to the drying oven. To avoid filling the drying oven 
with ether vapors, it is convenient to have a suction flask nd carbon 
tube near the Wiley extractor, and as soon as the ether extraction 
is completed the crucible, still very wet with ether, may be placed in 


32 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


the carbon tube and sucked dry, after which it is placed in the drying 
oven. 

If the qualitative examination has indicated the presence of 
ammonium nitrate, the drying of the material insoluble in ether 
should be carried out at 70° C. instead of 100° C., because at 100° 
an appreciable loss of ammonium nitrate results whereas at 70° the 
loss is slight. 

The periods of drying generally adopted are five hours at 95° to 
100°, and overnight or 18 to 24 hours at 70° C. Even at the higher 
temperature no error results by drying overnight unless ammonium 
salts or other volatile ingredients are present. A shorter time than 
five hours is probably sufficient in most cases, but the five-hour 
period has been adopted to cover all cases and obviates any necessity 
of an additional check weighing. 

The loss of weight represents all ether-soluble material plus the 
moisture originally present in the sample. 

The ether extract is transferred from the glass extraction tube to 
an evaporating dish of low pattern or to a small beaker previously 
weighed. The extraction tube is then washed out with a small 
quantity of pure ether, which is added to the ether extract in the 
evaporating dish. The contents of the evaporating dish are allowed 
to evaporate spontaneously; a number of hours are usually allowed 
for the evaporation, the best results being obtained when the period 
is overnight. After the ether has evaporated, the residue is thor¬ 
oughly dried by leaving the dish for a few hours in a vacuum desic¬ 
cator. The weight is then noted; it is usually a little less than the 
total loss on ether extraction minus the moisture as determined by 
desiccation. The difference is due to volatilization of the nitro¬ 
glycerin during the evaporation of the ether, and is considered later. 

A more nearly correct value for the weight of material removed by 
ether is obtained by deducting the amount of moisture determined by 
desiccation from the total loss of weight found by extraction, the 
direct weight of the ether extract after the evaporation of ether 
being used only as a check. In all cases ether extraction should be 
made in duplicate, one sample of the weighed extract being used 
for the determination of the nitroglycerin with the nitrometer, and 
the other sample being used in determining the other constituents 
present. 

SUCTION METHOD. 

In the laboratories of some dynamite works extraction with ether 
is made without any form of continuous-extraction apparatus; the 
sample in the Gooch crucible is merely washed several times by 
pouring ether through it, applying suction after each addition of 
ether. This method involves the use of greater quantities of ether, 


BUREAU OF MINES 


BULLETIN 51 PLATE II 



A. APPARATUS FOR ETHER EXTRACTION. WILEY EXTRACTOR. 



B. 


GRAVIMETRIC BALANCE. 









DYNAMITE. 


33 


and the objection has been made that the reduction of temperature 
resulting from the evaporation of ether causes a deposition of mois¬ 
ture from the air current drawn through the sample, this moisture 
dissolving out small amounts of the water-soluble nitrates that pass 
through with the next addition of ether. 

To test the merits of this method in comparison with the usual 
extraction method, ether extractions were made on a large number 
of samples of 45 per cent dynamite, using both the reflux-condenser 
method and the suction method. In the latter method about 100 
c. c. of ether in six portions was passed through each sample, each 
portion of ether being allowed to stand in the crucible for one minute 
before suction was applied. The suction was continued for periods 
of one-half minute to two minutes in order that different amounts of 
air might be drawn through the samples. The samples were then 
dried and weighed as usual. 

In general, extraction in the Wiley apparatus gave slightly lower 
results than the suction method, although in most cases the difference 
between duplicate samples extracted by the same method was as 
great as the variation between the two methods. This fact is 
explained by the lack of homogeneity of the dynamite. For example, 
a few unusually large particles of wood pulp or nitrate in one sample 
may cause a greater variation in the percentage of ether extract than 
the variation actually due to the method of extraction employed. 

COMPARATIVE EXTRACTIONS WITH ANHYDROUS AND U. S. P. (96 PER 

CENT) ETHER. 

To ascertain the effect of the purity of the ether used for extrac¬ 
tions, determinations of ether extracts were made on several types of 
explosives, and on various carbonaceous absorbents used in dyna¬ 
mites. Duplicate determinations were made using both anhydrous 
ether (distilled over sodium) and U. S. P. (96 per cent) ether. 

Results of extractions are shown in the following table, the values 
given being the percentage of loss of weight noted on weighing the 
insoluble portion after drying five hours at 95° to 100°. The loss of 
weight in each case therefore includes any moisture originally present. 

67709°—Bull. 51—13-3 


34 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


Loss of weight of explosives and of carbonaceous absorbents by ether extraction . 



Kind of ether. 

Kind of sample. 

U. S. P. (96 
per cent). 

Anhydrous. 

Dynamite (A) . 

Per cent. 
25.86 

Per cent. 
25.69 

Dynamite (B) . 

32.58 

32.51 

Dynamite (C) . 

40.77 

40.74 

Com meal .. 

14.81 

14.92 

Wheat flour ... 

13.18 

13.12 

Wheat middlings . 

14.91 

14.78 

Com meal, dry. 

1.81 

1.71 

Wood pulp, dry (1). 

2.71 

2.18 

Wood pulp, dry (2) . 

2.59 

2.20 

Wood pulp, dry (3). 

2.31 

1.85 

Wood pulp (4) . 

8.84 

8.02 

Wood pulp (5). 

5.44 

4. 73 

Wood pulp (6) . 

5.98 

5.48 

Wood pulp (7) . 

12.24 

11.98 

Wood pulp (8) . 

13.30 

12. 75 

Wood pulp (9) ... .-. 

5.65 

5.23 

Wood pulp (10). 

6.23 

5.88 

Wood pulp (11). 

5.01 

4.85 

Wood pulp (12). 

7.74 

7.40 

Wood pulp (13). 

8.27 

7.86 



From the table it is apparent that U. S. P. ether extracts a larger 
percentage of material from the commonly used carbonaceous 
absorbents than does anhydrous ether, which is practically free from 
alcohol. It is probably because of the alcohol present, in amounts 
up to about 4 per cent, that U. S. P. ether shows the greater extractive 
power. 

EFFECT OF MOISTURE IN DYNAMITE ON EXTRACTION WITH ETHER. 

Numerous authorities prescribe that the ether extraction shall be 
made on a sample previously dried to constant weight in a desicca¬ 
tor.® Presumably this specification is aimed to prevent water- 
soluble constituents from being carried through in the ether extract. 
Such an error is naturally greater as the amount of moisture present 
in the dynamite is greater. Accordingly experiments were made on 
mining explosives similar to ordinary dynamite, to which water had 
been added as an additional constituent for the purpose of reducing 
the temperature of explosion. Two explosives containing 10.70 and 
5.70 per cent of moisture, respectively, were extracted with ether in 
the usual manner, (1) in the original condition, and (2) after having 
been dried in vacuum desiccators over sulphuric acid for 24 hours. 
The amounts of materials soluble in ether extracted are shown in the 
following table. 

* Guttman, O., Schiess-und Sprengmittel, 1910, p. 162; Kedesdy, E., Sprengstoffe, 1909, p. 247; Escales, R., 
Die Ejplosivstoffe, vol. 3,1908, p. 204. 






























DYNAMITE. 


35 


Res ults of ether extraction of two explosives in different conditions. 


1 

2 

8 

4 

5 

Sample. 

Condition. 

Moisture. 

Extract. 

Difference. 

A 

B 

i i 

Per cent. 
10.70 
.44 
5.70 
.45 

Per cent. 
26.52 

0 25.93 
25.79 

0 25.43 

Per cent. 

} 0.59 

i .36 


o Calculated to explosive in original condition. 


The amount of moisture present in the dried samples was found 
by desiccating portions of each sample for a further period of three 
days in ordinary sulphuric-acid desiccators. 

The values in column 4 represent the total loss on extraction less 
the moisture content of the sample, all results being expressed as 
a percentage of the amount of original undried explosive. 

Assuming that the extracts from the samples in their original 
condition (condition 1) are larger than those from the dried samples 
(condition 2) because of loss of water-soluble nitrate in the moisture 
taken up by the ether, it is apparent that in the case of ordinary 
dynamite containing only one or two per cent moisture any loss from 
this source is negligible. 

DETERMINATION OF NITROGLYCERIN. 

The nitrogen of organic or inorganic nitrates or nitrites is readily 
evolved as nitric oxide (NO) by reaction with sulphuric acid and 
mercury in the nitrometer. A determination of such nitrogen in 
the extract therefore serves as a means of calculating the amount 
of nitroglycerin present. The form of nitrometer found by the 
authors to be most satisfactory for explosives work is the modified 
Lunge nitrometer, as illustrated in Plate III. 

THE NITROMETER. 

This instrument ° consists of six glass parts as follows: A globe- 
shaped reservoir (a); a generating bulb (6) of about 300 c. c. capacity, 
the generating bulb having stopcocks at both top and bottom to 
permit a violent agitation, and having a cup above which communi¬ 
cates with the bulb through the upper stopcock; a second globe- 
shaped reservoir (c), to which, by means of a glass multiple connect¬ 
ing tube and rubber tubing, are joined a compensating burette ( d ), a 
reading burette (e ), and an additional measuring burette (/). The read¬ 
ing and compensating burettes are of the same shape and size, and 

a The description has been taken in a large part from a paper by J. R. Pitman on The analysis of nitric 
and mixed acids by du Pont’s modification of the Lunge nitrometer, Jour. Soc. Chem. Ind., vol. 19, 1900, 
p. 983; see also Lunge, G., Du Pont’s nitrometer, Jour. Soc. Chem. Ind., vol. 20, 1901, p. 100. 










36 ANALYSIS OF BLACK POWDEK AND DYNAMITE. 

are blown out into bulbs at the top. The compensating burette is 
not graduated. Above the bulb it has a small vertical open tube, 
which is sealed when the instrument is standardized. The reading 
burette is calibrated so that percentages of nitrogen may be read 
therefrom, and is marked to read from 10 to 14 per cent, being 
graduated to one-hundredths of 1 per cent. Between 171.8 and 
240.4 c. c. of gas must be generated to obtain a reading; that is, 
the 10 per cent mark represents the volume of 171.8 c. c. of NO 
at 20° and 760 mm. pressure, containing 0.1 gram of nitrogen; the 
14 per cent mark is equal to 240 c. c. NO under the same condi¬ 
tions, representing 0.14 gram nitrogen. 

The compensating burette is supported by a ring; the generating 
bulb is supported just above each stopcock by forked holders, 
curved so as to retain the bulb in place. In order to remove the gen¬ 
erating bulb it needs only to be raised slightly and brought forward, 
the manipulation of a screw, as with an ordinary clamp, being thus 
avoided. The two reservoirs and the reading burette are supported 
by ring clamps, these clamps having milled rollers at the shank; 
they are moved up and down vertical racks by means of hand 
screws, the rollers being so arranged in conjunction with the ver¬ 
tical racks that the weight of the part presses them down and acts 
as a brake, thus preventing their moving when not being manipulated. 

Having arranged the apparatus and filled the compensating, 
reading, and generating tubes as well as their connections with 
mercury, the next step is to standardize the instrument. Twenty 
to thirty cubic centimeters of sulphuric acid is run into the gener¬ 
ating bulb through the cup at the top, and at the same time about 
210 c. c. of air is let in; the cocks are then closed and the bulb is well 
shaken; this shaking thoroughly desiccates the air, which is then 
run into the compensating burette until the murcury is about on a 
level with the 12.50 per cent mark on the reading burette, the two 
burettes being held at the same height. The compensating burette 
is then sealed off at the top. A further quantity of air is desiccated 
in the satne manner and run over into the reading burette until the 
height of mercury in the reading burette stands at about the 12.50 
per cent mark. The cocks are then closed, and a small piece of 
glass tubing, filled with sulphuric acid (not water), and bent in the 
form of a U, is attached to the outlet of the reading burette. When 
the mercury columns are about balanced and the inclosed air has 
been cooled to room temperature, the cock is again carefully opened, 
and when the sulphuric acid balances in the U tube, and the mercury 
columns in both burettes are therefore at the same level, the air in 
each tube is subject to the same conditions, namely, atmospheric 
temperature and pressure. A reading is now made from the burette, 


BUREAU OF MINES 


BULLETIN 51 PLATE III 







! ;sss 


NITROMETER 


















































- 





* 
































* 


























































I 


























•i 




















0 































I 





















» 






















































- • 




♦ 























































» 




DYNAMITE. 37 

and the barometric pressure and temperature are carefully noted. 
Using the well-known formula 

V / P / (273+t)(l-.000]8O 

V “ P(273+« / )(l-.00018t) 

the volume this inclosed air would occupy at a pressure (P) of 29.92 
inches of mercury (760 mm.) and at a temperature (t) of 20° C. is 
determined. The cock is again closed and the reservoir and reading 
burette carefully adjusted so as to bring the air in the reading burette 
to the calculated volume and the mercury in the compensating burette 
to the same level as the mercury in the reading burette. A strip of 
paper is now pasted on the compensating burette at the level of the 
mercury, and the standardization is then complete. 

There is, however, another and shorter method of standardization 
than the one described above. It is well known that the quality of the 
sidphuric acid used in the nitrometer will materially affect the results. 
To ascertain whether sulphuric acid is suitable for use in making nitro¬ 
gen determinations in the nitrometer a determination is made on 
chemically pure dry potassium nitrate and the reading obtained in 
the nitrometer is compared with the theoretical percentage of nitrogen 
in potassium nitrate. In applying this procedure to the standardiza¬ 
tion of the nitrometer the compensating burette is filled with desic¬ 
cated air, as described above, and 1 gram of potassium nitrate, dis¬ 
solved in 2 to 4 c. c. of water, is introduced into the generating bulb, 
the cup is washed with 20 c. c. of 95 to 96 per cent sulphuric acid in 
three or four portions, and each portion is run separately into the 
bulb. The gas, when generated, is run over into the reading burette, 
and the mercury columns in both burettes are leveled, so that the 
mercury in the reading burette is also at 13.87, the theoretical per¬ 
centage of nitrogen in potassium nitrate. A strip of paper is pasted 
on the compensating burette at the level of the mercury, and the 
standardization is then accomplished. 

This method of standardizing offers many advantages over that 
first described, among which may be mentioned that no readings of 
temperature or pressure are necessary. Probably the greatest 
advantage is that if the acid used in standardizing should contain 
impurities, which might otherwise affect the result, the error is en¬ 
tirely compensated and corrected in subsequent work; that is to say, 
the instrument having been so standardized that the reading gives the 
theoretical percentage of nitrogen in potassium nitrate, the results 
will be accurate when testing other substances so long as the same 
quantity of sulphuric acid from the same lot is used. 

It must, of course, be understood that once having standardized 
the instrument with a certain lot of acid no different lot of acid can 
be used without restandardizing. In order to avoid slight differences 



38 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


in results due to variations in the acid, it is advisable to reserve a 
sufficiently large uniform stock of acid, for example, a carboy full, 
for nitrometer use. 

The additional measuring burette, with which this type of nitrom¬ 
eter is provided, known as the “universal tube” (/, PI. Ill), is simply a 
straight burette, marked to read from 0 to 100 in percentages and 
graduated to one-tenth of 1 per cent. The tube is of such a size that 
0.30 gram of NO (or gram-molecule of NO) under standard 
conditions of temperature and pressure (20° and 760 mm.) fills it to 
the 100 mark. 

If it is desired to read the percentage of nitrogen direct, 0.14 gram 
of substance is weighed out; if the percentage of N0 2 is desired, 
0.46 gram of substance is weighed out. Consequently, if 1.01 grams 
of potassium nitrate, 0.63 gram of nitric acid, or 0.85 gram of sodium 
nitrate are used, the results can be read directly as percentages of 
the original substance. 

This method is convenient when it is not certain that the reading 
will fall within the limits of the graduations in the ordinary measur¬ 
ing burette. 

The “universal tube” is found particularly advantageous when, 
for example, the amount of nitroglycerin in a sample is so small that 
the volume of gas generated is insufficient to fill the large reading 
burette to its graduated portion. The volume of gas generated from 
any amount of nitroglycerin up to about 0.75 gram may be read in 
the “universal tube.” Readings in this measuring tube can be as 
accurately made as in the regular reading burette. 

PROCEDURE. 

To determine the amount of nitroglycerin in the ether extract of a 
dynamite, the sample from which the ether has been evaporated is 
dissolved in 5 to 10 c. c. of sulphuric acid (specific gravity, 1.84) and 
transferred to the generating bulb of the nitrometer, the beaker and 
the cup of the nitrometer being rinsed with several further additions 
of acid until 20 to 25 c. c. has been used. If the quantity of nitro¬ 
glycerin present is too great, the sample dissolved in sulphuric acid 
is transferred to a burette and an aliquot part run into the nitrometer 
cup and washed into the generator with about 20 to 25 c. c. of sul¬ 
phuric acid. The maximum amount of pure nitroglycerin used should 
be not greater than 0.75 gram in order that the gas generated will not 
exceed the volume of the reading burette. 

The generator is then shaken gently until the generation of gas 
has forced out all but about 60 to 75 c. c. of the mercury, the reser¬ 
voir being lowered if necessary in order to reduce the amount of 
mercury to this extent. The cock at the bottom of the generator 
is then closed and the generator shaken violently for about two to 


DYNAMITE. 


39 


three minutes. After allowing all bubbles to separate from the 
reaction mixture, the gas is transferred to the reading burette, the 
surface of the mercury in the burette is brought to the same level 
as that in the compensating burette when the dry air in the com¬ 
pensating burette occupies the standard volume indicated by the 
strip of paper attached in calibrating. 

The gas is allowed to stand for a few minutes to obtain an equi¬ 
librium of temperature, the levels being readjusted if necessary, 
and the reading is noted. This reading divided by 18.50 equals the 
weight of nitroglycerin in the sample used for the determination. 

A more or less serious error to be considered in the determination 
of nitroglycerin is that introduced by losses due to volatilization 
of the nitroglycerin during the evaporation of the ether. To deter¬ 
mine the effect of the rapidity of evaporation on the amount of 
nitroglycerin lost, weighed samples (0.6 to 0.7 gram) of nitroglycerin 
were placed in 100 c. c. beakers, tieated with 50 c. c. of ether, the 
ether evaporated at different rates, and the samples dried in vacuum 
desiccators to remove the moisture taken up during the evaporation 
of the ether. Nitrogen was then determined by means of the nitrom¬ 
eter, the weight of nitroglycerin being calculated from the nitrom¬ 
eter reading. The results obtained 1 are tabulated below: 

Loss of nitroglycerin on evaporating ether extract. 


[Determinations by J. H. Hunter.] 


1 

2 

3 

4 

5 

6 

7 

Sample. 

Original 
weight of 
sample. 

Weight of 
residue 
after evap¬ 
oration of 
ether. 

Nitrometer 

reading. 

Weight of 
nitroglycerin 
found by 
nitrometer.** 

Loss of 
nitro¬ 
glycerin 
(2-5). 

Method of evaporation. 

1. 

Oram. 

0.6469 

Oram. 

0.6458 

Per cent. 
11.73 

Oram. 

0.6389 

Oram. 

0.0080 

At room temperature over¬ 
night. 

2. 

.6328 

.6318 

11.53 

.6280 

.0048 

3. 

.6212 

.6140 

11.17 

.6084 

.0128 

Gentle boiling. 

Do. 

4 

.6643 

.6375 

6.0268 

5. 

.6199 

.6167 

11.31 

.6160 

.0039 

Do. 

G . 

.6666 

.6660 

11.96 

.6514 

.0152 

Current of compressed air 
blown over beaker. 

Do. 

7. 

.6773 

.6710 

12.10 

.6590 

.0183 




a Weight of nitroglycerin=nitrometer reading-i- 18.50. & Loss of weight. 


No attempt was made to obtain constant weight after evaporation 
of the ether, the samples being left in vacuum desiccators only long 
enough to remove most of the water; hence the weights in column 
3 are greater than the weights of nitroglycerin calculated from the 
nitrogen found (column 5). 

The figures in column 6 represent the differences between the 
weights in columns 2 and 5. 




















40 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


It was noted that rapid removal of the ether, either by means of 
gentle heating or by means of an air current, caused a greater loss 
of nitroglycerin than did slow spontaneous evaporation at room 
temperature, the only exception being in the case of sample 5, with 
which the loss of nitroglycerin was only 0.0039 gram, the ether being 
volatilized by gentle boiling. The large loss noted with sample 4 
was probably due to spurting. 

Such losses as are shown in the table do not greatly affect the 
determination of nitroglycerin in a sample of dynamite. Thus, in 
analyzing a 6-gram sample of dynamite, a loss of 0.01 gram of nitro¬ 
glycerin would be equivalent to only 0.17 per cent of the original 
sample. The importance of the error is of course greater as the 
percentage of nitroglycerin in the sample is less. 

Evaporation in the bell-jar evaporator .—An improved method of 
removing the ether from the ether extract without appreciable loss 
of nitroglycerin was devised by A. L. Hyde in the bureau's labora¬ 
tory. The beaker containing the ether solution is placed on a 
ground-glass plate and covered by a glass bell jar about 6 inches in 
diameter and 8 inches high, having two tubulures, one at the top 
and one on the side, each opening being fitted with a perforated 
stopper and delivery tube. A rapid current of compressed air, 
dried by passage through concentrated sulphuric acid, in two wash 
cylinders, is allowed to enter through the glass tube in the top of the 
bell jar, the lower end of the tube being about one-half inch above 
the surface of the ether solution in the beaker. The air current is so 
regulated that a marked “ dimple" is made in the surface of the 
solution, care being taken to prevent any loss by spattering. The 
possibility of acid being mechanically carried over from the cylin¬ 
ders is avoided by connecting an empty trap between the cylinders 
and the bell jar. The ether vapors pass out through the glass tube 
in the side tubulure and may be conducted out of the laboratory 
through a rubber tube passing to a hood or out of a window. 

The low temperature produced by the rapid evaporation of the 
ether minimizes the volatilization of the nitroglycerin, and the fact 
that the air is thoroughly dried prevents any deposition of moisture 
in the beaker, so that it is not necessary to desiccate the residue 
after the ether has entirely volatilized. 

The following preliminary tests show the efficiency of the method: 
A weighed quantity of nitroglycerin was dissolved in 50 c. c. of ether, 
the ether evaporated as described, and the residue in the beaker 
weighed at intervals. 


DYNAMITE. 


41 


Loss of nitroglycerin by evaporation of ether solution in bell-jar evaporator . 


Time of 
evapora¬ 
tion. 

Weight of sample. 

A 

B 

C 

D 

Hours. 

Grams. 

Grams. 

Grams. 

Grams. 

0 

a 2.838 

a 3. 236 

a 2.979 

a 2.620 

2 

3.176 

3.359 

3.189 

2.801 

3 

2.941 

3.286 



4 

2.881 

3.262 

3.037 

2.644 

5 

2.863 

3.251 



0 

2.856 

3.245 

2.987 

2.623 

7 

2.851 

3.241 

2.984 

2.621 

9 

2.843 

3.236 

2.978 

2. 619 

11 

2.841 

3.235 

2.977 

2.618 

14 

2.837 

3.234 




a Original weight of nitroglycerin. 


U. S. P. ether (96 per cent) was used in tests A and B, and alcohol- 
free ether (distilled over sodium) in tests C and D. When the 96 per 
cent ether was used a distinct odor of acetic aldehyde was noticed 
and the rate of loss of weight was slightly lower, due no doubt to the 
presence of alcohol in the ether. 

It is apparent from the above results that this method offers a con¬ 
venient and rapid method of removing the ether without appre¬ 
ciable loss of nitroglycerin. Evaporation for about six hours 
removes the ether sufficiently to permit determination of the nitro¬ 
glycerin in the nitrometer. 

DETERMINATIONS OF SULPHUR, RESINS, ETO. 

The sulphur used in dynamite is the form known as crushed brim¬ 
stone. It is soluble in about 100 parts of ether at 23.5° C.,° and 
unless present in large amount in the sample of explosive being 
analyzed it will all be removed by the extraction with ether. How¬ 
ever, when a considerable amount of sulphur crystallizes out in the 
ether extract, it is always advisable, after the water extraction, to 
make a further extraction of the explosive with carbon disulphide, 
in order to insure the complete removal of the sulphur. 

As already mentioned, the analysis of an explosive is carried out 
in duplicate, one sample of the ether extract being used lor the de¬ 
termination of nitroglycerin, the duplicate sample being used for the 
determination of sulphur, resins, etc. The duplicate sample is treated 
as follows: The weighed extract is redissolved in a mixture of ether 
and alcohol previously neutralized with standard alkali. The solu¬ 
tion thus obtained is titrated with standard alcoholic potash to deter¬ 
mine resins, phenolphthalein being used as an indicator. Determi¬ 
nations of a number of samples of commercial rosin (colophony) 
gave rather uniform results, 1 c. c. of normal alkali being found 


a Gody, L., Traite th6orique et pratique des matures explosives, 1907, p. 85. 














42 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


equal to 0.34 gram of rosin, which agrees with the value given by 
Lewkowitsch. 0 

After titration a large excess of alcoholic potash is added and the 
mixture is heated on the steam bath, preferably overnight, in order 
to saponify the nitroglycerin. It must be remembered that nitro¬ 
glycerin so treated saponifies slowly. Hence the reaction must not 
be hastened by heating to a higher degree than that obtained on a 
water bath, as an explosion may result. When saponification is com¬ 
plete the residue left upon evaporation is shaken with water and ether 
and separated in a separatory funnel. Any oily material (vaseline, 
paraffins, etc.) that can not be saponified is dissolved in the ether and 
may be weighed after evaporation. The water solution is acidified 
with hydrochloric acid and treated with bromine to oxidize the 
sulphur. Any rosin that was originally present will have formed a 
soap with the alkali; the acid decomposes this soap, and the rosin 
separates out from the acid liquid, floats on it, and may be readily 
removed, dried, and weighed, the weight serving as a check on the 
results of titration. The sulphur is oxidized to sulphuric acid by the 
bromine and may be determined by precipitation as barium sulphate. 

Sulphur may be separated from nitroglycerin by a method depend¬ 
ing on the fact that nitroglycerin is soluble in 70 per cent acetic acid, 
whereas sulphur dissolves only slightly in either glacial or 70 per cent 
acetic acid. The extent to which sulphur dissolves in acetic acid 
was determined by experiments with both brimstone and flowers of 
sulphur, in both cases the material being pulverized so as to pass 
through an 80-mesh sieve. 

One gram of sulphur was digested in 100 c.c. of acetic acid for a 
definite period of time; the mixture was then washed on to a weighed 
Gooch crucible, dried for five hours at 70°, and weighed. The loss in 
weight represented the amount of sulphur dissolved by 100 c. c. of 
acid. The results were as follows: 


Solubility of sulphur in acetic acid. 
[Determinations by J. H. Hunter.] 


Form of sulphur. 

100 c. c. of 70 per cent acetic 
acid. 

100 c. c. of glacial aceflc acid. 

Temper¬ 

ature. 

Time. 

Weight of 
sulphur 
dissolved. 

Temper¬ 

ature. 

Time. 

Weight of 
sulphur 
dissolved. 


° C. 

Hours. 

Oram. 

° C. 

Hours. 

Gram. 



1 

0.000 

25 

1 

0.0338 

Brimstone. 

1 25 

25 

.000 

25 

1 

.0354 


1 2° 

1 

.0226 

80 

1 

. 1658 


( 80 

1 

.0127 

80 

1 

.1464 


| 25 

20 

.0115 




Flowers of sulphur 

25 

20 

.0090 





1 80 

1 

.0027 





l 80 

1 

.0036 





« Lewkowitsch, J., Chemical technology and analysis of oils, fats, and waxes, vol. 1,1909, p. 502 




















DYNAMITE. 


43 


These determinations show that sulphur (brimstone) can be sepa¬ 
rated from nitroglycerin by means of acetic acid (70 per cent) at ordi¬ 
nary room temperature without appreciable loss of the sulphur. 

EXTRACTION WITH WATER. 

The determination of water-soluble constituents is made on the 
dried and weighed residues left in the crucibles after extraction with 
ether. The apparatus used consists of an ordinary heavy-walled 
side-neck suction flask provided with a rubber stopper, through which 
passes a carbon filter tube. The crucible is inserted in the top of the 
filter tube, a tight joint being obtained by means of a short length 
of thin-w T alled rubber tubing. As the analysis is made in duplicate, 
two suction flasks so arranged are connected to a Y tube, and both 
samples are extracted at once. A Bunsen valve or an empty bottle 
to serve as a trap should be inserted between the Y tube and the 
suction pump to guard against any tendency of the water to “suck 
back.” 

Cold water is used for the extraction because hot water would 
partly gelatinize any starch that might be present, and hot water 
would also remove more soluble organic material from the wood pulp. 
The water is passed through each sample in small quantities (about 
20 c. c.) at a time. The sample is covered with water, allowed to stand 
a short time, and suction applied until all the water has passed into 
the flask. This process is repeated until at least 200 c. c. of water has 
been used. If each portion of water is allowed to stand on the sample 
for a short time and then thoroughly sucked out, this quantity of 
water is more than sufficient for complete extraction, but in case of 
doubt a few drops of the last portions of the filtrate is tested by evapo¬ 
ration on a glass plate. 

If starch is present the filtration often proceeds very slowly because 
of the tendency of the starch to separate at the bottom of the crucible 
and form an almost impermeable layer on top of the asbestos mat. 
In such cases the use of stronger suction simply increases the density 
of this mass and retards rather than aids filtration. When any con¬ 
siderable quantity of starch has been detected in the qualitative 
examination, it is advisable to make use of porous alundum crucibles 
for the analysis, since these allow the filtrate to pass through the 
walls above the dense material at the bottom. With these crucibles 
it is necessary to use carbon tubes of such diameter that the crucible 
projects the greater part of its depth into the tube, being held by the 
rubber about one-fourth inch from its top. If this is not done there 
is a tendency for the filtrate to leak out of the crucible above the 
rubber. 


44 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


These porous crucibles have been found decidedly convenient, 
especially in the case of materials that tend to clog the ordinary 
Gooch crucible. 

The water extraction having been completed, the crucibles, with 
their contents are again placed in the drying oven and dried for five 
hours at about 95 to 100° C. No additional loss results from longer 
drying at this temperature, and frequently to save time samples are 
dried overnight. After cooling in a desiccator the crucibles are 
weighed and the loss of weight noted. This loss of weight repre¬ 
sents the total water-soluble material, and, in addition to the water- 
soluble salts detected in the qualitative examination, includes organic 
extract from the wood pulp, flour, or other absorbent. When cereal 
products are present the amount of organic material thus extracted 
may amount to 2 per cent or more, including sugars, etc., that form 
constituent parts of the grain. Frequently the antacid used, generally 
calcium carbonate or magnesium carbonate, is attacked by acid 
decomposition products from the nitroglycerin, a portion of the car¬ 
bonate being thereby converted to nitrate or nitrite. In such cases 
some calcium or magnesium is found in the water extract. 

Usually the only water-soluble constituent to be considered in an 
ordinary dynamite is an alkaline (sodium or potassium) nitrate. 
When an approximate analysis only is desired it is generally con¬ 
sidered sufficient to regard the total loss of weight on extraction as 
nitrate, but as shown above, this frequently gives erroneous results. 

DETERMINATION OF ALKALINE NITRATES. 

The method best suited for determination of nitrates is the follow¬ 
ing: An aliquot portion of the water extract is evaporated to dryness 
on a water bath and the residue gently ignited to burn off the organic 
matter. After cooling, the sides of the evaporating dish are washed 
down with a few cubic centimeters of water, about 1 c. c. of nitric 
acid is added, the evaporation repeated, and the residue heated gently 
over a burner until just fused, or the residue is dried in an oven at 
about 120° C. The treatment with nitric acid is necessary for the 
complete conversion to nitrate of any nitrite resulting from burning 
off the organic matter. The treatment should be repeated until the 
weight of the residue is constant. 

The weighed residue is calculated as percentage of nitrate in the 
original explosive. Since this weight necessarily includes any non¬ 
volatile water-soluble impurities originally present in the nitrate, as 
iron, aluminum, chlorides, sulphates, etc., for an exact analysis it is 
necessary to ascertain the amount of such impurities by volumetric 
or gravimetric determinations on fresh aliquot portions of the water 
extract, or a direct determination of the true nitrate content may be 
made in the nitrometer as described on the following page. 


DYNAMITE. 


45 


DETERMINATION OP ALKALINE NITRATES BY MEANS OF THE NITROMETER. 

An aliquot portion of the water extract estimated to contain 
the proper amount of nitrate for determination in the nitrometer 
(about 0.6 to 0.8 gram of NaN0 3 or 0.8 to 1.0 gram of KN0 3 for 
the type of nitrometer previously described, p. 35) is evaporated 
almost to dryness on a steam bath and transferred, by means of as 
little water as possible, to the cup of the nitrometer. The amount of 
water used should not exceed 20 c. c. This solution is drawn into 
the generator, and 30 to 40 c. c. of sulphuric acid (95 to 96 per cent) 
is added slowly, in small quantities at first to avoid generating suf¬ 
ficient heat to crack the glass. Because of the dilution of the acid 
the generation of the gas proceeds much more slowly than in the 
determination of nitroglycerin, and it is necessary to shake the gen¬ 
erator for a total time of about 8 to 10 minutes in order to be certain 
that the reaction is complete. The volume of gas is measured and 
the percentage of nitrate is calculated in the same manner as in the 
case of nitroglycerin. This method is excellent for use as a check or 
for an exact determination of the actual nitrate content. 

Tests made on a 1 per cent solution of pure potassium nitrate by 
both the gravimetric and volumetric methods described above gave 
results as follows: 

Results of determinations of nitrates in a water solution by the gravimetric and by the 

volumetric method. 

[Determinations by J. H. Hunter.] 


Test 

Volume of 
solution 
used. 

Weight 
of KN0 3 
used. 

Gravimet¬ 

ric 

method. 

Volumetric method. 

No. 

Weight 
of KN0 3 
found. 

Reading 
of nitrom¬ 
eter (N). 

Weight 
of KN0 8 
found. 

1 

c. c. 

100 

Grams. 

1.0000 

Grams. 

0.9994 


Grams. 

2 

100 

1.0000 

13.92 

1.0036 

3 

100 

o1.0000 

.9997 

4 

100 

a 1.0000 

13.92 

1.0036 

5 

100 

&1.0000 

1.0004 

6 

100 

b 1.0000 

13.93 

1.0043 




n Two one-hundredths gram of sugar was added to the 100 c. c. of nitrate solution. 
b Two one-hundredths gram of sodium chloride was added to the 100 c. c. of nitrate solution. 

EXTRACTION WITH ACID. 

As already pointed out, the materials most commonly used as 
antacids are the carbonates of calcium or magnesium or the oxide of 
zinc. Frequently ground dolomite is used, in which case both cal¬ 
cium and magnesium must be determined. The qualitative exam¬ 
ination will have shown, however, what acid-soluble materials are 
present. 

















46 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


The procedure to be followed in making the acid extraction depends 
on whether or not starch is present in the explosive. In either case 
the dried and weighed residue insoluble in water is used for the 
treatment with acid. 

In the absence of starch a simple extraction is made with cold 
dilute hydrochloric acid (1:10), 100 c. c. being drawn through the 
sample in the crucible in small successive portions, as described 
under “Extraction with water’ ’ (p. 43). Several portions of water 
are then drawn through to wash out the acid, and the crucible with 
the insoluble residue is dried as before for five hours at 95 to 100° C. 
It is sufficiently accurate to use this ‘ Toss-of-weight” figure as the 
-amount of antacid, as the amount of organic material extracted 
from the wood pulp will be very small, but if greater accuracy is 
desired a quantitative determination of the dissolved base or bases 
may be made by the usual gravimetric methods 

DETERMINATION OP CALCIUM. 

Calcium is determined as follows: An excess of ammonium hydrox¬ 
ide is added and the solution boiled. Any precipitate of iron or 
aluminum hydroxides may be filtered off, ignited, and weighed, but 
the amount of such impurities is usually so small that it may be 
disregarded and calcium precipitated without previous filtration. 
Hot ammonium-oxalate solution is added in slight excess to the 
boiling solution and the boiling is continued for a short time. The 
precipitate is allowed to settle completely, and then is filtered, dried, 
and weighed as CaC 2 0 4 , or is ignited and weighed as CaO. 

DETERMINATION OF MAGNESIUM. 

Magnesium is determined in the filtrate from the calcium deter¬ 
mination by concentrating to about 100 c. c., adding an excess of a 
solution of sodium hydrogen phosphate to the hot solution, then a 
large excess of ammonium hydroxide, and allowing the phosphate 
precipitate to separate completely by standing for several hours. 
The precipitate is filtered in a Gooch crucible, washed, ignited, and 
weighed as Mg 2 P 2 0 7 . 

DETERMINATION OF ZINC. 

Zinc is precipitated with Na 2 C0 3 solution as carbonate, ignited, 
and weighed as ZnO. If ammonium salts are present the zinc is 
precipitated with H 2 S as ZnS, the ZnS filtered off, redissolved, and 
precipitated as carbonate. The determination of zinc is more fully 
considered in the discussion of ammonia dynamites on page 58. 





DYNAMITE. 


47 


DETERMINATION OF STARCH. 

When starch is present both the starch and the antacid are removed 
in one operation by boiling with dilute acid, whereby the starch is 
rendered soluble by conversion to dextrin. In carrying out this 
process the material in the crucible is moistened with water and 
completely transferred with a spatula, or by washing with a stream 
of water from a wash bottle, into a beaker of about 500 c. c. capacity. 
If a Gooch crucible is used the asbestos is removed with the residue 
and the clean crucible dried and weighed. From the original weight of 
the crucible plus the asbestos the weight of the asbestos is ascertained 
and deducted from the final weight of dried residue remaining after 
hydrolysis. The volume of water in the beaker is made up to about 
250 c. c., and about 3 c. c. hydrochloric acid (specific gravity 1.2) is 
added, and the mixture is stirred and brought to boiling over a 
burner. Boiling is continued until the starch is entirely hydrolized, 
a drop of the acid mixture being tested from time to time on a spot 
plate with a solution of iodine in potassium iodide until a blue color¬ 
ation is no longer obtained. Longer boiling will only result in loss 
of extractive material from the wood pulp. 

The boiled material is then at once filtered through a fresh crucible 
or through the original porous crucible, if such was used, washed 
several times with water, dried as before, and weighed. If the 
figures representing the weight include the weight of the asbestos mat 
from a Gooch crucible, the proper correction for the weight of the 
asbestos is made as noted above. 

The amount of antacid contained in the acid filtrate is ascertained 
by a gravimetric determination as previously described. 

It has already been noted (p. 44) that small amounts of soluble 
organic material (sugars, dextrin, etc.) from flour or other cereal 
products and extract from the wood pulp will be found in the water 
solution. In summarizing the results of analysis it is of course 
impossible to know what portion of such extracted organic material 
constituted part of the flour and what portion should properly be 
added to the wood pulp. Similarly, the organic material dissolved 
during the acid hydrolysis includes not only such portions of the 
grain as starch and gluten but soluble portions of the wood pulp. 

It is customary in quoting the results of analysis to include all 
such soluble organic material from both water and acid extractions 
under the term “starch,” and the insoluble residue is designated 
as “wood pulp and crude fiber.’’ In other words, the weight of 
insoluble residue dried at 100° is called “wood pulp and crude fiber,” 
whereas the sum of this constituent and of the ingredients determined 
in the ether, water, and acid solutions, deducted from the weight of 
original sample, is called u starch.” 


48 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


In the case of a dynamite which contains no cereal product, the 
sum of the determined ingredients deducted from the weight of 
original sample is taken as the amount of wood pulp present and 
includes the material extracted from the pulp by the water and acid 
treatment as well as the insoluble residue found by direct weight. 

The actual amounts of wood pulp and of cereal products added in 
manufacture can not therefore be definitely determined, since por¬ 
tions of each will be found in the ether, the water, and the acid 
extractions as well as in the insoluble residue. 

In order to determine to what extent the wood pulp in a dynamite 
is affected by the various extractions, etc., necessary in the course 
of analysis of the dynamite, dried samples of various grades of pulp 
were submitted to the treatment through which the insoluble wood 
pulp residue in a sample of dynamite had passed. 

Samples of 2 to 3 grams of wood pulp were weighed in Gooch 
crucibles, dried to constant weight, and extracted successively with 
ether, water, and cold hydrochloric acid (1:10), and then boiled for 15 
minutes with dilute hydrochloric acid (1:100). The latter treatment 
would be necessary if starch were present with the wood pulp in an 
explosive. After each operation the sample was dried five hours at 
100°, and the loss of weight was determined. The results were as 
follows: 

Results of analyses of wood pulp. 


Sample 

No. 

Loss of weight (per cent of dry sample.) 

Percentage 
of insol¬ 
uble 
residue. 

Extraction 
with ether. 

Extraction 
with cold 
water. 

Extraction 
with cold 
HC1(1:10). 

Boiling 
with HC1 
(1:100) 

1. 

2.66 

2.57 

1.41 

5.91 

87.45 

2. 

2.78 

2.89 

.42 

1.75 

92.16 

3. 

2.09 

2.23 

.53 

3.93 

91.22 

4. 

1.95 

2.84 

1.03 

4.83 

89.35 


These experiments show that the final insoluble residue that is 
weighed as wood pulp may be only about 90 per cent of the amount 
of dry wood pulp actually present in the dynamite. A part of the 
loss is determined as rosin in the ether extract, and the portions 
extracted with water and hot acid are calculated as starch (if starch 
has been determined). When starch is not present the error in the 
determination of pulp is much less as the boiling-acid treatment is 
dispensed with. The analysis can then be made accurate by direct 
determination of the water-soluble nitrate and of the antacid as 
described above, and the amount of wood pulp can be found by 
subtracting the sum of the percentages of moisture, nitroglycerin, 
alkaline nitrate, and antacid from 100 per cent. This amount will 
be in excess of the percentage of insoluble residue found, according 
to the amounts of pulp extracted by the water and acid. 














DYNAMITE. 


49 


EXAMINATION OF INSOLUBLE RESIDUE. 

DS^ERMINAIxCN up wood pulp, etc. 

The residue that remains after the ether extraction, the water ex¬ 
traction, and the extraction with dilute acid is usually a mixture of 
wood pulp, sawdust, or other form of cellulose or lignin. When corn 
meal, flour, middlings, bran, etc., are present in the dynamite, the resi¬ 
due will contain the nonstarchy portions of these materials, either free 
or mixed with wood pulp. In general, ordinary dynamite contains 
wood pulp alone as the absorbent, but low-freezing dynamites and 
“ straight’' dynamites containing less than 40 per cent of nitro¬ 
glycerin often contain considerable quantities of corn meal, 'wheat 
middlings, or low-grade flour. 

Infusorial earth was formerly much used as an absorbent for nitro¬ 
glycerin, but in recent years it has seldom been so used in this coun¬ 
try, having been almost entirely replaced by an active base or dope. 

If the hydrochloric acid has not been thoroughly washed from the 
insoluble residue, the wood pulp will considerably darken in color 
during the drying process. From its physical structure, as observed 
without magnification, or with a small lens, much information may 
be gained in regard to the probable composition of the insoluble 
residue, 4>ut in all cases the examination is best made under the 
microscope, with a low-power objective, one of 32-mm. focus being 
suitable. One of the duplicate samples of insoluble residue is used 
for microscopic and chemical examination, and one for the deter¬ 
mination of ash. A small amount of the sample which is to be used 
for microscopic and chemical examination is removed from the 
crucible, placed upon a microscope slide, and moistened with one 
or two drops of water. By means of a platinum needle the material 
is then carefully spread out, but no cover glass is used. Wood 
pulp, the most common constituent in the residue of ordinary dyna¬ 
mite, will be seen as separate fibers or bunches of fibers of very 
characteristic appearance. 

In Plate IV, A and B, wood pulp of different grades is illustrated, 
and the characteristic appearance of sawdust or dust from certain 
types of woodworking machinery is shown in Plate IV, 0. The 
bundles or clusters of fibers are characteristic of such materials. 
Typical samples of infusorial earth (kieselguhr) are shown in Plate 
IV, D and E. It should be noted that, as plainly shown in the figures, 
widely differing types of infusorial earth exist, forms of organisms 
appearing in one sample which will not be found in another. The 
general appearance of shell remains is a definite indication of. the 
presence of diatomaceous or infusorial earth. The sample shown 
in Plate IV, D, was obtained, through the courtesy of Dr. G. P. 


67709°—Bull. 51—13-4 



50 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


Merrill, from the National Museum, Washington, D. C. (Specimen 
No. 6555, from Cornwallis, Nova Scotia.) ,^ 

The appearance of the “husks ’ 1 or crude fiber from vheat 

flour (middlings), after hydrolysis of the starch, is shown in Plate 
IV, F; the cellular structure of the irregularly shaped particles of 
fiber is readily seen. 

A and B, Plate V, represent cellulose (cotton) and nitrocellulose, 
respectively. These two materials can not be distinguished from 
each other by microscopic examination in ordinary light, but in 
polarized light a decided difference is noted, the unnitrated fibers 
appearing in brilliant colors and the nitrated fibers dark. 

In the case of the presence of cereal products it is often of value to 
make a microscopic examination of the residue insoluble in water 
before hydrolysis of the starch. In Plate V, C, D, and E, such 
materials are shown. C represents ordinary fine wheat flour; D, 
wheat flour mixed with wood pulp; E, coarse wheat flour or mid¬ 
dlings; and F, corn meal. Characteristic differences in the appear¬ 
ance of the starch granules of wheat and corn are of aid in identifying 
these cereals, the wheat starch granules being in general well rounded 
or oval, whereas the cornstarch granules are almost always dis¬ 
tinctly polygonal in shape. 

DETERMINATION OF ASH. 

The remaining sample of residue from acid extraction is used for 
the determination of ash, and may be either incinerated in the cruci¬ 
ble that has been used for extraction, or the residue, together with the 
asbestos mat, may be removed to a platinum crucible and ignited; 
in this case there is subtracted from the ash the known weight of 
asbestos present in the mat. The ash of an ordinary dynamite, con¬ 
taining only wood pulp, sawdust, or corn meal as absorbents, will 
seldom amount to more than 0.20 per cent. When the amount of ash 
present is as much as 0.5 per cent the ash should in all cases be 
examined under the microscope to determine the possible presence 
of infusorial earth or other inorganic material (pulverized glass, sand, 
etc.), provided the presence of these materials has not already been 
detected by the microscopic examination. A high ash content may 
also indicate that either the water or acid extractions have not been 
complete. In this respect the ash determination may be regarded 
as a check on the analysis. 

VARIATIONS DUE TO METHOD OF ANALYSIS. 

In order to ascertain to what extent the results of analysis of a 
dynamite would be effected by variations in the method of analysis, 
uniform samples of a 45 per cent dynamite were submitted to the 
laboratories of 11 explosives works, with the request that analyses be 


BUREAU OF MINES 


BULLETIN 51 PLATE IV 




A. WOOD PULP NO. 1 (x 50). 


B. WOOD PULP NO. 2 (X 50). 



C. SAWDUST (X 25). 






E. INFUSORIAL EARTH NO. 2 (X 150). 



F. CRUDE FIBER FROM WHEAT MID- 
DLINGS (X 25) 



































« 
























* 



























































































f 






















-1 







DYNAMITE. 


51 


made by the methods regularly in use in each laboratory and results 
reported, together with brief notes as to the method used. 

The samples were prepared as follows: Fifty cartridges of a lot of 
45 per cent dynamite were opened, about two-thirds of each cartridge 
removed (the ends being rejected), and broken up finely in a porce¬ 
lain dish by means of a horn spoon. All of these portions were then 
mixed together very thoroughly in a large porcelain dish. From this 
uniform mixture about 20 sample bottles (150 c. c. capacity) were 
filled, the contents of each bottle then being emptied out separately 
into a dish, carefully mixed again, and replaced in the bottle. Each 
sample represented about 150 grams. 

Eleven of these samples were sent to different laboratories, as noted 
above, and seven of them analyzed in the bureau’s explosives chemi¬ 
cal laboratory by different analysts. Careful instructions were sent 
with each sample, that, in order to compensate for any segregation 
occurring in shipment, the entire sample should be thoroughly mixed 
before analysis. 

The results of the analyses of these samples are shown in the fol¬ 
lowing table: 

Analyses of uniform samples of dynamite. 


1 

2 

3 

4 

5 

6 

7 

Sample 

No. 

Moisture. 

Nitro¬ 

glycerin. 

Potas¬ 
sium ni¬ 
trate. 

Calcium 

carbon¬ 

ate. 

Wood 

pulp. 

Nitroglycerin. 

By direct 
weighing. 

By ni¬ 
trometer. 

A 

B 

C 

D 

E 

Fa 

G 

H 

J 

Kb 

L 

M 

N 

0 

PI 

P2 

P3 

Q 

1.21 

.89 

.99 

.91 

1.05 

1.02 

.41 

1.35 

1.22 

43.90 
44.99 
44.77 
45.25 
44.52 
42.29 

44.91 
44.86 
44.98 

39.14 
38.40 
38.75 
38.62 
38.05 
41.02 
39.04 
38.09 
38.48 

1.02 

1.15 

1.06 

.98 

1.28 

1.15 

1.12 
1.28 
.99 

14.73 
14.57 
14.59 

14.24 
15.10 
14.52 
14.52 

14. 42 
14.37 









:::::::::: 


. 


. 








1.60 

1.00 

1.19 
1.15 
1.04 
1.26 
.98 

1.18 

44.50 
45.70 

45.50 
45.48 
45.35 
45.22 
45.24 
45.42 

37.40 

37.57 

37.54 

37.69 

37.66 

37.33 

37.87 

37.60 

1.00 

1.17 

1.15 

1.16 
1.10 
1.20 
1.21 

1.19 

15.50 

14.56 

14.62 

14.52 

14.85 

14.88 

14.70 

14.61 







45.87 

45.31 

45.22 

45.17 



45.41 

45.14 


a The remarkable difference noted in the analysis of this sample as compared with all other samples, is 
due to the fact that, through misunderstanding, this sample was not mixed on being received. After 
several analyses had been made with widely varying results, the remainder of the sample was mixed by 
rubbing through sieves. This treatment probably resulted in considerable loss of nitroglycerin. Sample 
F is therefore not considered in the discussion of results. 
b No report received. 


Samples A to L were analyzed in the laboratories of various powder 
companies and samples M to Q in the bureau’s laboratory; P2 and 
P3 were analyzed by men under instruction, not members of the 
laboratory force of the bureau. 






























52 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


DISCUSSION OF ANALYSES. 

MOISTURE. 

The methods employed were as follows: 

Samples E, J, and M to Q, inclusive—3 grams desiccated on watch 
glass over H 2 S0 4 for 3 days (0.98-1.26 per cent). 

Sample A—6 to 10 grams on watch glass, 3 days over H 2 S0 4 
(1.21 per cent). 

Sample B—3 grams on watch glass, 2 days over CaCl 2 (0.89 per 
cent). 

Sample D—6 grams on watch glass, 24 hours over H 2 S0 4 in vac¬ 
uum (0.91 per cent). 

Sample C—2 grams on watch glass, 24 hours over H 2 S0 4 , 15 inches 
vacuum (0.99 per cent). 

Sample H—5 grams in Gooch crucible, 48 hours over H 2 S0 4 at 
40° C. (1.35 per cent). 

Sample G—10 grams in 4-ounce bottle, dry-air current passing 
over surface of sample for 24 hours (0.41 per cent). 

Sample L—10 grams in drying tube, dry-air current passing through 
sample for 24 hours (1.60 per cent). 

It is noted that desiccation on a watch glass over H 2 S0 4 for three 
days gave only 0.3 per cent maximum variation, results obtained 
with the aid of vacuum for 24 hours being a little low. Two days 
over CaCl 3 gave low results. High results were obtained by desic¬ 
cating at 40° C. and by passing dry air through the sample, from 
loss of nitroglycerin under these conditions. Passing dry air over 
the surface of the sample gave low results, as might be expected. 

NITROGLYCERIN. 

The results obtained in the bureau’s laboratory with samples M to 
Q varied from 45.22 to 45.70 per cent. Samples of 5 to 10 grams in 
Gooch crucibles were extracted for one hour with U. S. P. ether (96 
per cent) in the Wiley apparatus and the residues dried five hours 
at 100° C. The loss in weight minus the moisture previously deter¬ 
mined was taken as the nitroglycerin content. Samples B, E, and J 
were analyzed in the same manner, giving results from 44.52 to 
44.99 per cent. Samples A, C, D, G, and L were extracted with 
ether by means of suction, 7 to 10 grams of sample being treated 
with five or six successive portions of ether (amounts varying from 
50 to 120 c. c.). Samples A, C, and D were dried to constant weight 
in steam ovens after extracting (the time of drying not noted); G 
was dried at 100° to 105°, and L for two hours at 95°. The results 
varied from 43.90 to 45.25 per cent. The results obtained in the 
bureau’s laboratory (45.22 and 45.70 per cent) are uniformly higher 
than those obtained in other laboratories (43.90 to 45.25 per cent). 




BUREAU OF MINES 


BULLETIN 51 PLATE V 





E. WHEAT FLOUR (MIDDLINGS) (X 50). F. CORN MEAL (X 50). 






















DYNAMITE. 


53 


Nitrometer determinations on three samples (column 7) showed the 
true nitroglycerin content of the evaporated ether extracts to be 
approximately 45.2 per cent. 

No explanation can be given for the large number of results in 
which the amounts of nitroglycerin found are uniformly low, except 
failure to observe one or more of the following precautions: (1) The 
extraction must be complete; (2) the residue must be dried to con¬ 
stant weight at a temperature of about 100° C.; (3) the dried resi¬ 
due must be cooled in an efficient desiccator and weighed as soon as 
cooled. 

POTASSIUM NITRATE. 

The results obtained in the bureau’s laboratory varied from 37.33 
to 37.87 per cent. The determination was made by extracting the 
residue insoluble in ether with about 200 c. c. of water, and deter¬ 
mining the nitrate in an aliquot part of the water solution by evap¬ 
oration, as described on page 44. No correction was made for traces 
of chlorides, etc., in the solution. The determination on sample H 
was made in the same manner, giving 38.09 per cent, while on sample 
L an aliquot portion of the water extract was analyzed in the nitro¬ 
meter with a result of 37.40 per cent. All the remaining samples 
were extracted with water, the insoluble residues dried at about 100C°. 
and weighed, the loss of weight being regarded as potassium nitrate. 
This method gave high results (38.05 to 39.14 per cent) owing to the 
water-soluble organic matter extracted from the wood pulp. 

CALCIUM CARBONATE. 

In samples L to Q the calcium carbonate was determined gravi- 
metrically in the dilute-acid extract; in samples C and D by direct 
titration of the residue insoluble in water, or of the ash left after 
burning off the pulp; in A, B, E, and J the loss of weight on extrac¬ 
tion with dilute acid was considered as calcium carbonate, while in 
G and H the ash was assumed to be entirely calcium carbonate. The 
variations are of minor importance and no conclusions can be drawn 
from the results. 

WOOD PULP. 

Variations in the method of determining the potassium nitrate 
influence the proportion of wood pulp reported. When the loss of 
weight on extracting with water is assumed to be entirely potassium 
nitrate, in spite of the fact that it contains considerable organic 
matter extracted with the wood pulp, the proportion of wood pulp 
found will be lower than if the nitrate is determined by a direct 
method and the wood pulp by difference. The percentage of wood 
pulp being found by subtracting the sum of all other constituents 
from 100 per cent, no comparison of results is possible. 


GELATIN DYNAMITE. 


Unlike ordinary dynamite, which contains nitroglycerin absorbed 
in a porous material, gelatin dynamite contains nitroglycerin com¬ 
bined with nitrocellulose to form a plastic solid. When nitroglycerin 
is warmed with nitrocellulose containing about 12 per cent of nitro¬ 
gen, the nitroglycerin dissolves the nitrocellulose, and a thick, vis¬ 
cous mass is produced which resumes a jelly-like consistency as soon 
as it has cooled. When as little as 3? per cent of nitrocotton is dis¬ 
solved in nitroglycerin at 60°, the material should form a jelly-like 
nonflowing mass when cooled to ordinary temperatures, but when 
smaller amounts of nitrocellulose are used the viscosity of the solu¬ 
tion becomes less. The explosive known as “blasting gelatin” 
consists of about 93 to 90 per cent of nitroglycerin and 7 to 10 per 
cent of nitrocellulose, and is a translucent, jelly-like mass, containing 
the highest percentage of nitroglycerin used in any solid explosive. 

Any explosive containing nitroglycerin combined with nitrocellu¬ 
lose in connection with an active base consisting of a nitrate and 
combustible material is termed a “gelatin dynamite.” The gelatin 
dynamites have many properties that make them desirable for mining 
work, their greatest advantage being that they are almost unaffected 
by water. 

SAMPLING. 

The coherent, pasty, doughlike consistency of gelatin dynamite 
renders the preparation of a uniform sample much more difficult than 
is the case with ordinary dynamite. 

A sample is prepared from one or more cartridges by cutting off 
portions from different parts of each stick; these portions are then 
cut into thin pieces and broken up as finely as possible by means of an 
aluminum or platinum spatula. The use of a steel spatula or knife 
is not to be recommended. The sample so prepared is well mixed 
and bottled, and because of its tendency to form a solid mass again 
on standing, it should be analyzed as soon as possible after being 
prepared. 

The ingredients that may be found in the various types of gelatin 
dynamite are nitroglycerin; nitrocellulose; sulphur; rosin; sodium, 
potassium, or ammonium nitrate; calcium or magnesium carbonate; 
wood pulp; and cereal products. 

Moisture is determined in the manner previously described. 

54 



GELATIN DYNAMITE. 


55 


The extraction with ether is made as for dynamite except that ether 
distilled over sodium (that is, ether free from alcohol) is used in order 
to avoid the partial solution of the nitrocellulose. Nitrocellulose is 
insoluble in pure ether, but a small percentage of alcohol present as an 
impurity may cause the solution of a considerable proportion of this 
constituent, and as the amount of nitrocellulose is usually only 0.5 to 
2 per cent its determination should be accurate. 

The ether solution containing the nitroglycerin, sulphur, and rosin 
is treated in the manner already described, and the water extraction 
of the dried and weighed insoluble residue is made in the usual way. 

SULPHUR. 

If the percentage of sulphur is unusually high, or if the extraction 
with ether has not been continued long enough, some sulphur may 
remain in the dried residue left after water extraction, in which case 
an additional extraction is made with carbon disulphide in the Wiley 
apparatus, the same method as described for the ether extraction being 
used. After the extraction with carbon disulphide has been made, the 
crucibles should be sucked dry and the carbon disulphide allowed to 
evaporate in a warm place before the crucibles are placed in the oven, 
as the vapors of carbon disulphide are very inflammable and may 
ignite in the oven. The crucibles with their dried residue are weighed 
and the loss of weight considered as sulphur. 

The extraction with water is next made as before described. 

NITROCELLULOSE. 

Nitrocellulose is now removed by means of a suitable solvent. 
The pyroxylin cotton usually employed as a gelatinizing agent is 
soluble in a mixture of two parts ether and one part alcohol, but as 
all grades of nitrocellulose are more readily soluble in acetone than in 
ether alcohol it is customary to use acetone as the solvent. 

The extraction with acetone is made by separating the dry residue 
from the crucible, leaving the mat intact if possible, placing the 
residue in a small beaker and covering it with acetone. The mixture 
is allowed to stand for three to four hours, with frequent stirring to 
dissolve completely the nitrocellulose, and is then filtered through the 
original crucible, washed with acetone, dried in the usual manner, and 
weighed. The loss of weight represents nitrocellulose plus a small 
amount of extract from the wood pulp. The wood pulp extract is 
usually so small that it may be disregarded, but a check on the nitro¬ 
cellulose determination may be made by evaporating the acetone 
solution to a small volume (about 20 c. c.), and diluting gradually 
with a large volume of hot water (about 100 c. c.), which drives oft* 
the volatile solvent, precipitating the nitrocellulose as a white floc- 
culent mass. The precipitate is then filtered off, dried, and weighed 
as nitrocellulose. 


56 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


The remainder of the analysis is conducted as is that described 
for straight dynamite. 

Some of the older types of gelatin dynamites contained small 
amounts (1 to 2 per cent) of paraffin, but this is an unusual ingredient 
and is more frequently found in ammonia dynamite. (See p. 57.) 

Ammonia gelatin dynamite is a type that has of recent years 
assumed commercial importance. It differs from ordinary gelatin 
dynamite in the fact that it contains ammonium nitrate in addition 
to the usual constituents of the former. As in the ammonia dyna¬ 
mites, discussed later, so here the ammonium nitrate is usually pre¬ 
viously coated with vaseline, paraffin, or other waterproofing mate¬ 
rial, and is neutralized with zinc oxide. 

In the analysis of gelatin dynamite it should be remembered that 
trade custom has led to an erroneous system of designating the 
strength of explosives of this class. Thus a gelatin dynamite con¬ 
taining about 30 to 33 per cent of nitroglycerin and about 1 per cent of 
nitrocotton is called a “ 40 per cent ’ ’ strength gelatin dynamite. This 
unfortunate practice undoubtedly had its origin in the fact that, as 
gelatin dynamite is much denser than ordinary dynamite, and a 
greater quantity can therefore be placed in a hole, it was assumed to 
be stronger. Comparative tests indicate that, weight for weight, 
a so-called “40 per cent’ ’ strength gelatin dynamite containing 33 per 
cent nitroglycerin is much weaker than is an ordinary “ straight ’ 9 
dynamite containing 40 per cent nitroglycerin. 


AMMONIA DYNAMITE. 


The usual type of ammonia dynamite is practically a “straight” 
dynamite in which a large part of the nitroglycerin is replaced by 
ammonium nitrate. Sulphur is sometimes a constituent of this 
type of explosive, and frequently the wood pulp is wholly or largely 
replaced by coarse flour or middlings. The ammonium nitrate is 
generally protected from hygroscopic influence by a coating of vaseline 
or paraffin and is neutralized with zinc oxide. These ingredients are 
added to the ammonium nitrate in the course of its manufacture 
while the crystals of the ammonium nitrate are still hot. 

In the analysis of such explosives the determination of moisture 
and extractions with ether, water, and acid are carried out as pre¬ 
viously described. An additional extraction with carbon disulphide 
is usually necessary in order to remove all of the sulphur; this is done 
after the water-soluble salts have been extracted. 

One portion of the ether extract is used for the determination of 
nitroglycerin in the nitrometer and the other for the determination 
of the sulphur and vaseline or paraffin. 

The method for the analysis of the ether extract as described on 
pages 41 and 42 is the scheme of separation followed when both sulphur 
and vaseline, or paraffin, are present with the nitroglycerin, although 
several other methods are applicable and give reliable results. 

The nitroglycerin may be destroyed by means of caustic alkali, 
which also dissolves any resin present; the solution is decanted 
from the residue of paraffin, or vaseline, and sulphur; the resin is 
precipitated with hydrochloric acid, filtered, dried, and weighed. 
The residue of sulphur and paraffin or vaseline is treated with hot 
ammonium sulphide which dissolves the sulphur; this solution is 
cooled, decanted, and the vaseline or paraffin adhering to the beaker 
is washed, dried, and weighed. The weight of sulphur is found by 
difference.® 

The water extract contains both ammonium and sodium nitrates, 
together with water-soluble organic material from the flour or other 
absorbent. If zinc oxide has been used as the antacid, all of this 
component will generally be found in the water extract, since the 
small amounts used are readily soluble in ammonium nitrate solutions. 


• Gody, L., Traite tMorique et pratique des matures explosives, 1907, pp. 388-389. 

57 




58 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


An aliquot part of the water extract is evaporated in a platinum dish 
on a steam bath, the ammonium nitrate volatilized, and the organic 
matter burned off by careful heating over a burner. A little nitric 
acid is added to oxidize to nitrate any nitrite resulting from reduction, 
as described on page 44. In heating this residue care must be taken 
to avoid decomposition of the zinc nitrate, or else the heating should 
be strong enough to convert it entirely to zinc oxide. Either of the 
following methods may be usefi: 

(1) The residue, after evaporation of the nitric acid on the steam 
bath, is dried at about 110° to 120°, and weighed as NaN0 3 and 
Zn(N0 3 ) 2 . This residue is then dissolved in water and the zinc 
precipitated with sodium carbonate, filtered, ignited, and weighed 
as ZnO. The weight of NaN0 3 and Zn(N0 3 ) 2 minus (2.33 times the 
weight of ZnO) equals NaN0 3 . 

(2) The residue obtained as above is heated gently over a burner 
until the evolution of oxides of nitrogen from the decomposition of the 
zinc nitrate has ceased, care being taken that the temperature is not 
high enough to cause a loss of sodium nitrate. The residue is now 
weighed as NaN0 3 plus ZnO, then treated with water to dissolve the 
NaN0 3 ; the ZnO is filtered on a Gooch crucible, ignited, and weighed 
as ZnO, the NaN0 3 being found by difference from the combined 
weight. The filtrate containing the sodium nitrate should be tested 
with ammonium sulphide to assure that the zinc has been entirely 
converted to insoluble zinc oxide. 

Zinc may be determined in a separate portion of the water extract 
by adding ammonia, precipitating with hydrogen sulphide, and 
filtering off the precipitated zinc sulphide. The precipitate is 
washed and, without drying, dissolved in a small amount of nitric 
acid, and evaporated to dryness. Any free sulphur is thus oxidized. 
The residue is treated with a little sulphuric acid and again evaporated 
to dryness over a burner at a dull-red heat until the free acid has been 
volatilized. Little, if any, decomposition of the zinc sulphate 
results from this heating. The treatment with sulphuric acid and 
heating should be repeated until a constant weight of ZnS0 4 is 
obtained. This method is convenient and has been found to check 
well with the methods described above. 

Ammonium nitrate is determined directly with a separate portion 
of the water extract by the usual method of distilling from a solution 
made strongly alkaline with KOH, collecting the distillate in a 
known volume of standard H 2 S0 4 , and titrating the excess of acid 
with standard alkali, cochineal being used as an indicator. 

In regard to the determination of ammonium nitrate, the possible 
effects of several influencing factors have been investigated. Stillman 
and Austin state that ammonium nitrate is slightly soluble in ether,® 

a East, H.. Anleitung zur chemischen und physikalischen Untersuchungen der Spreng- und Zundstoffe, 
1909, p. 980. 




AMMONIA DYNAMITE. 59 

and several other authors have noted that correction should be made 
for this solubility. 

Ten-gram samples of pure ammonium nitrate were desiccated to 
constant weight over sulphuric acid and were extracted with U. S. P. 
(96 per cent) ether for one hour in the Wiley apparatus. On drying 
to constant weight in vacuum desiccators a maximum loss of only 
0.10 per cent was noted. Additional drying of the same samples 
at 70° for 18 hours caused a further loss of 0.07 to 0.15 per cent. 
On continuing the drying at 90° to 100° further losses calculated as 
percentages of the original sample were as follows: 

Loss in weight of ammonium nitrate dried at 90° to 100 


Time of 

Total loss 

, per cent. 

drying. 

Sample 1. 

Sample 2. 

Hours. 

2 

0.03 

0.04 

5 

.03 

.05 

24 

.07 

.11 

120 

.33 

.39 

240 

.62 

.67 


The above-mentioned experiments show that the loss of pure 
ammonium nitrate by the ether extraction and by subsequent drying 
for several hours at 70° or 100° is very slight—not over 0.25 per cent. 

That the loss on drying depends on the surface exposed was shown 
by drying, at 90° to 100°, 5-gram samples spread on 3-inch watch 
glasses. The losses were as follows: 

Loss in weight of ammonium nitrate dried on S-inch watch glasses at 90° to 100° C. 


Time of 

Loss of weight, per cent. 

drying. 

Sample 1. 

Sample 2. 

Hours. 

5 

0.34 

0.33 

24 

.88 

.98 

48 

2.03 

1.57 

120 

6.11 

4.64 

168 

7.09 

5.84 


In this case the much greater surface of samples exposed caused a 
much more rapid volatilization. 

In the analysis of an explosive containing zinc oxide, it must be 
remembered that in addition to mere volatilization there is possible 
still further loss from the decomposing action of the ZnO on the 
ammonium nitrate. This is shown by the following experiment: 
Two 10-gram samples of ammonium nitrate were ground in a mortar, 
0.5 gram zinc oxide being well mixed with one sample. The two 
samples were then placed in crucibles and heated at 100°. The 
losses in weight are given in the table following: 












60 ANALYSIS OF BLACK POWDER AND DYNAMITE. 

Loss in weight of ammonium nitrate with and without zinc oxide on heating at 100 ®. 



Loss in weight, per cent. 

Time. 

Ammo¬ 
nium ni¬ 
trate. 

Ammo¬ 
nium ni¬ 
trate plus 

5 per cent 
of zinc 
oxide. 

Hours. 

2 

0.02 

0.61 

18 

.11 

1.07 

48 

.16 

1.13 


The effect of too high temperature of drying is shown more clearly 
in the following experiments with an ammonium nitrate explosive of 
the “permissible” class, containing nitroglycerin. The explosive 
contained about 75 per cent of NH 4 N0 3 and 1.4 per cent of ZnO. 
Six 10-gram samples were extracted with ether in the usual manner 
to remove the nitroglycerin. Two of the extracted samples were 
dried over night at 100° C., two over night at 70° C., and two for 24 
hours in vacuum desiccators to constant weight. The samples were 
then extracted with water, dried five hours at 100° C., and the loss 
in weight noted. Ammonium nitrate was determined in the water 
solutions by the distillation method previously described. The 
results are tabulated below: 


Effect of different methods of drying ammonium nitrate explosives after ether extraction. 
[Determinations by J. H. Hunter.] 


Method of drying. 

Loss of weight, per cent. 

NH 4 NO 3 in water solu- 
• tion, per cent. 

Ether extraction. 

Water extraction. 

High. 

Low. 

Mean. 

High. 

Low. 

Mean. 

High. 

Low. 

Mean. 

In a 100° oven. 

In a 70° oven. 

In a vacuum desiccator. 

13.48 
11.72 
11.68 

13.10 
11.64 
11.57 

13.29 

11.68 

11.63 

77.58 

79.29 

79.22 

77.23 

79.09 

79.11 

77.40 
79.19 
79.17 

75.01 

75.31 

71.76 

74.78 

75.20 

71.76 

74.90 

75.25 


These results show clearly that drying at 100° after extraction 
with ether causes a considerable loss of ammonium nitrate, most 
of the loss being due to decomposition of the nitrate by the zinc 
oxide. 

The sum of the amounts of sodium nitrate, ammonium nitrate, 
and zinc oxide found in the water solution will be less than the total 
water extract, since the latter, as before noted, includes water- 
soluble organic material from the wood pulp, flour, or other carbona¬ 
ceous absorbents. This organic material is added to the amount 
of starch, etc., removed by hydrolysis and reported as “starch,” as 
has been noted on a previous page. 

























LOW-FREEZING DYNAMITE. 


Nitroglycerin congeals or freezes at a temperature of about 8° C. 
(46° F.), and as nitroglycerin in the frozen condition is much less 
sensitive to the action of a detonator than when in the liquid condi¬ 
tion, explosives containing frozen nitroglycerin usually fail to explode 
when attempts are made to use them. 

As the outdoor temperature for several months in the year is on 
the average below the temperature at which nitroglycerin explosives 
freeze, many efforts have been made to prepare low-freezing explo¬ 
sives, which, without being thawed, may be used at temperatures 
lower than that at which ordinary nitroglycerin explosives are 
frozen. Some types of nonfreezing explosives contain ammonium 
nitrate mixed with nitrostarch, nitrotoluene, or similar material, but 
those explosives to which the term “ low-freezing ” is usually applied 
contain nitroglycerin mixed with the liquid nitro toluenes, with 
crystalline dinitrotoluene or trinitrotoluene, with the nitrochlorhy- 
drins or other materials, it having been shown, for example, that 
20 per cent of dinitrochlorhydrin in nitroglycerin reduces the tem¬ 
perature at which the mixture will freeze to about —12° C.,° and by 
the use of mixtures of nitroglycerin and dinitrotoluene explosives 
are prepared which may be used at temperatures considerably below 
0°C. 

Many low-freezing explosives are marked with the designation 
“L. F .” upon their wrappers; but even in the absence of this notice 
of the nature of the explosive a low-freezing dynamite may frequently 
be distinguished by the odor of nitrotoluene, or by the color test 
for nitrosubstitution compounds made on the ether extract as 
described under ‘‘Qualitative examination,” on pages 17 and 18. 

DETERMINATION OF NITROSUBSTITUTION COMPOUNDS. 

With low-freezing dynamites the methods of sampling and of 
determination of moisture are carried out in the manner already 
outlined. The extraction with ether is also made in the usual 
manner, and one of the samples of ether extract is used, as outlined 
on a preceding page, for the determination of resins, sulphur, or 
other ingredients. The other sample of ether extract is used for 
the determination of the nitroglycerin and nitrosubstitution products. 

• Roewer, F. A., Proc. 6th Int. Cong. App. Chem., vol. 1,1906, p. 541. 

61 




62 ANALYSIS OF BLACK POWDER AND DYNAMITE. 

So far as is known by the writers, no satisfactory method has yet 
been found for the direct determination of nitrosubstitution com¬ 
pounds in the presence of nitroglycerin. The analysis of such mix¬ 
tures is generally made by determining the nitroglycerin by means 
of the nitrometer (p. 35), and finding the amount of nitrosubstitu¬ 
tion compound by difference. The nitrosubstitution compounds 
are not decomposed in the nitrometer as are the nitric esters. 

It is interesting to note, however, that if mononitrotoluene is 
present the amount of nitroglycerin found by means of the nitrom¬ 
eter does not represent the true amount of this ingredient in the 
mixture. It has been found a that a portion of the nitric acid 
liberated from the nitroglycerin by the action of the sulphuric acid 
used in the determination is taken up by the mononitro toluene present, 
the latter becoming quantitatively nitrated to dinitrotoluene. 
Thus, if the amount of nitroglycerin in the ether extract is not in 
excess of the theoretical amount required to yield sufficient nitrogen 
to convert all the mononitrotoluene to dinitrotoluene, no evolution 
of nitric oxide will result. In other words, the error in the deter¬ 
mination of nitroglycerin is equal to about 0.5530 gram of nitro¬ 
glycerin for each gram of mononitrotoluene present. Pure crystalline 
dinitrotoluene or trinitrotoluene was found to have no effect on the 
determination, and the same was found to be true of the so-called 
1 ‘liquid trinitrotoluene.” “Liquid dinitrotoluene,” however, causes 
an error amounting to 0.0628 gram of nitroglycerin for each gram 
of the nitrosubstitution product. This error was shown to be prob¬ 
ably due to the presence of mononitrotoluene in the liquid dinitro¬ 
toluene. 

These results show that the nitrometer method for determination 
of nitroglycerin is not reliable if mononitrotoluene is present. The 
latter is, however, seldom used in low-freezing dynamites, and in the 
case of the more commonly used liquid dinitrotoluene, the resulting 
error is not large. For example, in an explosive containing 25 per 
cent of nitroglycerin and 10 per cent of liquid dinitrotoluene, the 
error in the determination of nitroglycerin would amount to 0.628 
per cent, or the amount of nitroglycerin found would be 24.37 per 
cent instead of 25 per cent. 

Further information may be gained by determining the total 
nitrogen of both the nitroglycerin and the nitrosubstitution com¬ 
pound by a modification of the Kjeldahl method and deducting 
the nitrogen of the nitroglycerin, the difference being the nitrogen 
of the nitrosubstitution compound. From this nitrogen the amount 
of the latter can be calculated. This method is of value only if the 


a Storm, C. G., The effect of nitrotoluenes on the determination of nitroglycerin by means of the nitrom¬ 
eter, Proc. 8th Int. Cong. App. Chem., vol. 4,1912, p. 117. 



LOW-FREEZING DYNAMITE. 63 

nitrosubstitution compound has been identified by the preliminary 
examination. 

Another method for the determination of the total nitrogen of 
such mixtures, as well as the ester nitrogen, is that of Berl and 
Jurrissen,® in which a so-called “decomposition flask” is used. 
By means of sulphuric acid and a small amount of mercury in a 
vacuum the decomposition of nitroglycerin or other nitric ester is 
effected and the resulting volume of nitrogen oxide (NO) measured. 
A second sample of the mixture is treated in the same manner after 
a preliminary oxidation with chromic acid and sulphuric acid, 
whereby the total nitrogen is converted to nitrogen oxide (NO). 
The difference between the two volumes of nitrogen oxide (NO) 
equals that resulting from the nitrosubstitution compound. 

The remainder of the analysis—the extractions with water, acid, 
etc.—is conducted in the manner previously described and should 
present no further difficulties. 

a Berl, E., and Jurrissen, A. W., Uber gasvolumetrische Analyse mit dem “Zersetzungskolben” und 
die Stickstofibestimmung in rauchschwachen Pulvern. Zeitsclir. angew. Chem., vol. 23,1910, p. 241. 



GRANULATED NITROGLYCERIN POWDER. 


When ordinary dynamite is used in blasting any material of a 
consistency resembling that of earth or clay, little of the energy of 
the explosive does useful work, because the soft and compressible 
nature of the material blasted allows the greater part of the energy 
of the explosive to be used in compacting the material and in pro¬ 
ducing a cavity. Consequently, gunpowder has been largely used 
in all places where earth, clay, or other soft material was to be 
dislodged. In the blasting of the banks of railroad cuts there are 
often places where a soft, but somewhat consolidated material, inter¬ 
mediate between earth and hard rock, has to be blasted. Such a 
material might be a soft shale, for example, or a friable and easily 
crumbled sandstone, and for dislodging it neither ordinary blasting 
powder nor ordinary dynamite is particularly suitable. In the year 
1876 E. Judson patented an explosive consisting of a low-grade gun¬ 
powder made by heating and mixing together coal, sulphur, sodium 
nitrate, etc., granulating the mixture, and then coating this non¬ 
absorbent granulated dope with a small amount of nitroglycerin. 
The proportion of nitroglycerin used—often as little as 5 per cent— 
was such that had it been absorbed by the grains of explosive it 
would not have been capable of detonation, but by remaining wholly 
or largely upon the surface of the grains the use of a detonator 
brought about its explosion and the simultaneous ignition of the 
gunpowder base which it covered. Such an explosive, as a result 
of the detonation of the nitroglycerin, produces an initial blow 
sufficient to crack and fissure the partly consolidated material in 
which it is placed. The action of the gunpowder mixture that 
forms the larger part of the explosive so heaves and moves the 
broken-up mass as to make easy its removal with steam shovels. 

Granulated nitroglycerin powders, or “free-running” explosives, 
have been very much used in the excavation of earth and are com¬ 
monly known as Judson powder (after the inventor), bank powder, 
or railroad powder. In the analysis of low-grade granular powder, 
moisture is determined by the standard method, and the usual 
method of extracting with ether is followed. In the ether extract 
are usually found large proportions of sulphur, rosin, etc., besides 
the nitroglycerin. The proportion of sulphur commonly used in 
64 



GRANULATED NITROGLYCERIN POWDER. 65 

low-grade granular powder is so considerable that usually it is not 
all removed by extraction with ether. 

The determination of nitrates in the residue after ether extraction 
is made in the manner already outlined for ordinary dynamite; an 
additional extraction with carbon disulphide is necessary to remove 
the sulphur not extracted by means of ether. 

As antacids are seldom added to low-grade granular explosives, 
the extraction with dilute acid may generally be omitted; but if the 
qualitative examination has indicated the presence of an antacid, its 
determination is made as already described. 

The residue remaining after the extractions with ether, water, and 
carbon disulphide is usually bituminous coal, although charcoal or 
other carbonaceous material may be found. An examination under 
the microscope or with a hand magnifier will usually show with 
sufficient certainty the nature of the insoluble residue, and the 
presence of bituminous coal may generally be confirmed by a vola¬ 
tile-matter determination made by heating the solid residue in a 
small crucible over a Bunsen flame. 

The separation and determination of the ingredients of the ether 
and water extracts is carried out by the methods previously described. 

67709°—Bull. 51—13-5 


BLACK POWDER. 


The general term “ black powder” is applied to several explosives 
of nearly similar composition, including chiefly black blasting powder, 
black gunpowder, and black fuse powder. As their chemical exami¬ 
nation involves identical problems, they are here treated as one 
general class. 

Black blasting powder usually consists of a mixture of sodium 
nitrate, sulphur, and charcoal, whereas black gunpowder is generally 
a mixture of potassium nitrate, sulphur, and charcoal. The real 
difference between “ gunpowder” and black blasting powder is one 
of use, since some blasting powder containing potassium nitrate as 
the oxidizing material has been made, and, similarly, there is record 
of gunpowder having been made from sodium nitrate. Although 
black blasting powder is usually made in larger grains than gun¬ 
powder, yet for certain purposes, particularly for large cannon, 
grains of gunpowder have been made even larger in size than the cus¬ 
tomary kinds of blasting powder, and again finely granulated blasting 
powder has been made for use where a quick-acting explosive, yet 
one not so rapid as dynamite, was desired. 

The black-powder composition used in the ordinary miner’s safety 
fuse and known as “fuse powder” is much similar to the ordinary 
grade of gunpowder, but is of very fine granulation (usually 40 to 100 
mesh), and contains potassium nitrate as its oxidizing agent. 

PHYSICAL EXAMINATION. 

GRANULATION OR AVERAGE SIZE OF GRAINS. 

The determination of the granulation of black powder is made by a 
series of standard sieves, but this examination is not usually required 
in connection with chemical analysis, and can be made only where a 
large sample of the powder is available. The standard sizes of grains 
of black blasting powder, together with a statement of the size of 
screen through which the material will pass, is given in the following 
tabulation : a 


a Munroe, C. E., and Hall, Clarence, A primer on explosives for coal miners. Bureau of Mines, Bull. 17, 
1911, p. 17. 

66 





BLACK POWDER. 


67 


Relation between sizes of black blasting powder and separating sieve. 


Size of 
grains. 

Diameter of 
round holes 
in screens 
through 
which grains 
pass. 

Diameter of 
round holes 
in screens 
on which 
grains 
collect. 

ccc 

inch 

II inch 

cc 

|| inch 

II inch 

c 

U inch 

II inch 

F 

||inch 

II inch 

FF 

II inch 

js\ inch 

FFF 

vr inch 

■h inch 

FFFF 

inch 

(a) inch 


a Or 28-mesh bolting cloth. 


GRAVIMETRIC DENSITY. 

By “gravimetric density” is meant the “apparent specific gravity” 
of the explosive, or the ratio that the weight of the powder con¬ 
tained in a given volume bears to the weight of water that would 
exactly fill the same volume. Gravimetric density or apparent 
specific gravity is therefore not only a factor of the true density of 
the powder, but is also influenced by the size and the shape of the 
grains, since obviously the space occupied by voids, or the space 
between grains, must vary with the shape and size of the grains. 

The standard determination of gravimetric density is made by 
pouring the powder into a vessel, usually in the shape of the frus- 
trum of a cone, striking off with a straightedge all over that required 
to fill the measure, and then weighing the powder held by the re¬ 
ceiver. Plate II, B, shows a commercial type of gravimetric balance 
for this purpose. With this balance direct readings of the gravimetric 
density of a powder are possible without calculation. When so few 
determinations must be made as to make the use of a separate in¬ 
strument seem unnecessary, the determination of the weight of 
powder contained in a cylindrical graduate of known volume, or a 
standard pint or quart measure, may be made. In all cases the 
gravimetric density is the ratio expressed by dividing the weight 
of powder required to fill the measure even full by the weight of water 
from the same measure even full. 

The gravimetric density of black powders varies over a consid¬ 
erable range, from about 1 to 1.3. 

ABSOLUTE DENSITY. 

By “absolute density” is meant the true specific gravity of the 
powder, the air space between grains being disregarded and only the 
density of the grains being considered. Owing to the fact that both 
sodium and potassium nitrates are readily soluble in water, it is not 






68 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


possible to make this determination with black powder by the picnom- 
eter method with water, so that a number of instruments involving 
the use of mercury have been designed by different investigators. 

The form of instrument used by the Bureau of Mines is illustrated 
in figure 5, and was devised by one of the authors.® The apparatus 
consists of a reservoir and means for introducing within this reser¬ 
voir a picnometer bottle con¬ 
taining the powder whose 
density is to be determined. 
By opening the water-supply 
valve the mercury is raised 
within the reservoir, and on 
closing it and opening the 
waste-pipe valve the water 
pressure is removed from the 
mercury in the lower reser¬ 
voir. A Torricellian vacuum 
is thus created in the dome 
above the bottle; most of 
the air in the bottle escapes 
and is replaced with mer¬ 
cury. The operation is re¬ 
peated until the air in the 
bottle is completely replaced. 
With this instrument the de¬ 
termination of the absolute 
density of black powder may 
be quickly and accurately 
made. 

SAMPLING. 

About 50 to 100 grams of 
the original sample is crushed 
in small portions in a porce¬ 
lain mortar and passed through an 80-mesh sieve. All precautions 
are taken to avoid unnecessary exposure of the sample to the air 
during this treatment. If each portion is placed in a stoppered 
bottle as soon as sifted, there is no appreciable change in hygroscopic 
moisture content. The powdered sample is well mixed before its 
analysis is begun. 

a Snelling, W. O., Improved densimeter. Proc. 8th Int. Cong. App. Chem., vol. 4,1912, p. 105. (Chem. 
Abs., vol. 6,1912, p. 3524.) 



Figure 5.—Densimeter. 







































BLACK POWDER. 


69 


CHEMICAL EXAMINATION. 

The chemical examination of black powder consists essentially of 
the determination of the amounts of moisture, nitrate, sulphur, and 
charcoal present. The nitrate is readily separated from the sulphur 
and charcoal by the solvent action of water, and after the residue from 
water extraction has been carefully dried the sulphur may be readily 
separated from the charcoal by the action of carbon bisulphide, or 
other solvent. 

The charcoal is always determined by difference. After being 
dried the charcoal is usually ignited and its content of ash determined. 

DETERMINATION OF MOISTURE. 

The determination of moisture is carried out exactly as has been 
described in the analysis of dynamite (p. 20), a 2-gram sample being 
spread on a 3-inch watch glass and desiccated for three days over 
sulphuric acid. It is customary in some explosives laboratories to 
determine moisture on a sample that is crushed only sufficiently to pass 
through a 10 to 12 mesh sieve, because in further pulverization the 
moisture content of the powder may be influenced by atmospheric 
conditions. Comparative determinations have indicated, however, 
that unless there is undue exposure in preparing the sample the differ¬ 
ence in moisture content between the coarse and the finely powdered 
sample is slight, and since the nature of black powder is such that 
a finely powdered sample must be used for chemical analysis it is 
considered much more convenient to use the same for the moisture 
determination. 

Many authorities recommend that moisture in black powder be 
determined by drying in an oven at temperatures of 60° to 100° C. a 
As sulphur is more or less volatile at temperatures even slightly above 
ordinary, the authors thought it advisable to compare the relative 
merits of oven drying with the desiccation method. A series of deter¬ 
minations was therefore made on large, well-mixed samples of finely 
ground powder (80-mesh), 2 grams spread uniformly in a thin layer 
on a 3-inch watch glass being used for each determination. The 
samples heated in ovens were allowed to cool for 15 minutes in desic¬ 
cators before weighing. It was found necessary to make the weigh¬ 
ings as rapidly as possible in order to prevent increase of weight. The 
following results were obtained. 

a Lunge, G., and Berl, E., Chemisch-technische Untersuchungsmethoden, vol. 3, 1910, p. 116; Gutt- 
mann, O., Schiess- und Sprengmittel, 1900, p. 48. 





70 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


Results of determinations of moisture in black 'powder. 
SAMPLE A. 

[Determinations by W. C. Cope.] 


Time. 

Loss on 
desiccation 
over sul¬ 
phuric acid. 

Loss on 
drying at 
70°. 

Loss on 
drying at 
100°. 

Hours. 

Per cent. 

Per cent. 

Per cent.. 

1 


1.00 

1.05 

2 


1.00 

1.10 

3 


1.00 

1.15 

5 

72 

1.00 

1.00 

1.30 


SAMPLE B. 

[Determinations by C. A. Taylor.] 


1 


0.44 

0.57 

2 


.46 

.78 

3 


.50 

.94 

5 


.54 

1.07 

7 


.59 

1.19 

24 

0.42—0.47 

.74 

3.70 

72 

0.46—0.49 

. 



The analysis (calculated moisture free) of sample B was originally 
as follows: Sodium nitrate,74.07; sulphur, 10.09; charcoal 15.84. The 
sample dried 24 hours at 100°, with a loss of 3.70 per cent, was ana¬ 
lyzed with the following result: Sodium nitrate, 77.0; sulphur, 6.53, 
charcoal 16.47. It is therefore evident that there is a loss of sulphur 
from black powder at 100°, and that this loss is appreciable in even a 
few hours' heating, whereas at 70° the loss for periods of heating up to 
five hours is approximately the same as the moisture determined by 
desiccation. 

Desiccation gives practically constant weight in 24 hours, but as the 
loss of moisture takes place more slowly in coarser samples, a uniform 
period of three days has been adopted. 

Sulphur alone is slightly affected by temperatures up to 100° C. 
A sample of approximately 5 grams of powdered brimstone (80-mesh) 
was desiccated for two days over sulphuric acid without loss of weight. 
It was then dried five hours at 70° C., losing only 0.003 per cent; 
further drying for five hours at 97° caused a loss of only 0.01 per cent. 

EXTRACTION WITH WATER; DETERMINATION OF NITRATES. 

In the determination of nitrates by extraction with water, about 10 
grams of the finely ground sample is weighed in a Gooch crucible with 
asbestos mat and about 200 c. c. of water, in successive portions of 
15 to 20 c. c. each, is drawn through the sample by means of suction. 
The complete solution of the nitrate is hastened by the use of warm or 
hot water, although 200 c. c. of cold water is usually sufficient. The 
final portions of water passing through the crucible should be tested 
for soluble nitrate by evaporation on a glass plate, or an excess of 
strong sulphuric acid containing a few crystals of diphenylamine may 






















BLACK POWDER. 71 

be added to a few drops of the water, and an intense blue coloration 
will indicate the presence of nitrate. 

The extraction is made on duplicate samples as with dynamite. 
After the complete removal of the nitrate the crucibles containing the 
portion insoluble in water are placed in a drying oven at a temperature 
of about 70° and dried to constant weight, usually overnight, although 
five hours is generally sufficient. The percentage of loss of weight, 
minus the moisture content found as described above, represents the 
total water-soluble material, and includes, in addition to sodium or 
potassium nitrate, a small amount of water-soluble organic material 
from the charcoal and the impurities in the original nitrate, such as 
chlorides and sulphate. An aliquot portion of the water extract is 
evaporated to dryness on a steam bath, treated with a little nitric 
acid, again evaporated, heated to slight fusion, and weighed. (See 
p. 44.) For accurate analysis the amounts of chlorides and sul¬ 
phates may be determined in separate portions of the water extract 
and the true nitrate content determined by difference, or a direct 
determination of nitrate may be made with the nitrometer on a 
portion of the extract, as previously described. 

The water solution should, of course be tested to determine whether 
sodium or potassium nitrate is present. This determination is con¬ 
veniently made by heating to redness a clean platinum wire dipped 
in the solution, and observing the color of the flame through several 
thicknesses of cobalt glass. Potassium is indicated by its character¬ 
istic red color, and the yellow of the sodium flame is entirely cut off 
by the blue glass. Without the cobalt glass a sodium nitrate powder 
should give an intense yellow flame and a potassium nitrate powder a 
pale pink or lavender flame. If both sodium and potassium nitrates 
are indicated, a determination of potassium is best made by the 
sodium-cobalti-nitrate method of Drushel,® or the proportions of 
sodium and potassium nitrates may be calculated with an approxi¬ 
mate degree of accuracy from the total weight of nitrates found by 
evaporation and the percentage of nitrogen in the combined weight 
of these nitrates as determined by the nitrometer. 

The following illustrates the method of calculation employed: 

Let a = weight of both nitrates. 
x = weight of sodium nitrate. 

Then a — x = weight of potassium nitrate. 

Let b = percentage of nitrogen found in combined nitrates. 

16.47 = percentage of nitrogen in sodium nitrate. 

13.87 = percentage of nitrogen in potassium nitrate. 

Then 0.1647* + 0.1387 («-*) = 1 o^ 

a Bowser, L. T., The determination of potassium by the cobalti-nitrate method. Jour. Ind. and Eng. 
Chem., vol. 1, 1909, p 791. 




72 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


Solving for x gives the weight of sodium nitrate present in the mix¬ 
ture, and subtracting this from the total weight of the mixture gives 
the potassium nitrate. 

EXTRACTION WITH CARBON DISULPHIDE; DETERMINATION OF SULPHUR. 

The dried and weighed material left from the extraction with water 
consists of the sulphur and charcoal. The sulphur is determined by 
loss of weight on extraction with carbon disulphide in the Wiley 
extraction apparatus, the method being exactly the same as that 
used in the extraction with ether. 

Because of the fact that it is difficult to obtain carbon disulphide 
that does not leave a residue of sulphur on evaporation, it is not 
customary to evaporate the carbon-disulphide extract to dryness and 
weigh the sulphur dissolved from the powder. This may be done, 
however, if freshly distilled pure carbon disulphide is used. 

INSOLUBLE RESIDUE, CHARCOAL. 

The residue remaining in the crucibles is weighed directly as char¬ 
coal after drying to constant weight at about 100°. 

In drying the crucibles after the carbon disulphide extraction 
extreme care should be used to avoid setting fire to the inflammable 
vapor of the carbon disulphide, as it sometimes happens that the 
heavy vapor from the crucibles passes down to the flame by which 
the water oven is heated. Carbon disulphide has the lowest ignition 
temperature of any material not containing phosphorus, therefore in 
extracting with carbon disulphide, or in handling the crucibles after 
extraction, considerable care should be taken to avoid proximity to 
lights or fire. 

DETERMINATION OF ASH. 

The ash in the charcoal is determined by ignition over a Bunsen 
burner until all of the carbon has been burned off, and weighing. The 
ash is usually found to be about 0.5 to 1 per cent of the total powder. 
In case of an abnormally high ash value it is possible that the extrac¬ 
tion with water was incomplete, leaving some nitrate undissolved. 

The sulphur used in black powder is almost invariably brimstone, 
flowers of sulphur not being suitable for this purpose because of the 
invariable presence of acidity. 

In those cases where flowers of sulphur are used, however, it shouid- 
be noted that the extraction of the sulphur with carbon disulphide 
will be incomplete. Watts,® Gody, 6 and other authorities have called 
attention to the fact that flowers of sulphur always contain a con- 

« Watts’s Dictionary of Chemistry, 1905, vol. 4, pp. 606-610. 
b Gody, L., Traite th<5orique et pratique des matures explosives, 1907, p. 99. 



BLACK POWDER. 73 

siderable amount of insoluble amorphous sulphur, often amounting 
to as much as 35 per cent. 

Experiments made in the bureau's explosives laboratory with 
samples of brimstone and flowers of sulphur gave results as follows: 


Relative solubility of flowers of sulphur and brimstone in carbon disulphide. 



Weight of 
sample. 

Loss of 
weight on 
extraction, a 

Insoluble 

substances. 

Flowers of sulphur. 

Grams. 

/ 1.0907 

\ 1.0450 

f 1.1238 

\ 1.1004 

Grams. 

0.7817 
.7472 
1.1230 
1.0996 

Per cent. 
23.21 
28.50 
.07 
.07 

Brimstone. 



o Extracted two hours in Wiley extraction apparatus with carbon disulphide. 


In view of the fact that when flowers of sulphur are present the 
extraction with carbon disulphide is incomplete, some authors have 
recommended the use of hot aniline as a solvent for the sulphur. 

The solubility of sulphur in various solvents is shown in the follow¬ 
ing table : a 


Solubility of sulphur in 100 parts (by weight) of various solvents. 


Solvent. 

Tempera¬ 

ture. 

Parts (by 
weight) of 
sulphur 
dissolved. 

Carbon disulphide..............._............................................ 

°C. 

0 

23.99 


15 

41.65 


22 

46.05 


38 

94.57 


«*55 

181.34 

Benzene............_..................._......._........................ 

26 

.965 


71 

4.377 

Toluene..................................................... 

23 

1.479 


23.5 

.972 


22 

1.205 


174 

16.35 


130 

85.96 





a Boiling. 


Of these solvents carbon disulphide and aniline are the ones that 
would appear to be of greatest practical value in analysis. Carbon 
tetrachloride, chloroform, and benzene have also been used with success 
as solvents for sulphur, but their use requires long-continued extraction. 

Experiments have been made in the explosives laboratory of the 
bureau to determine the suitability of aniline as a solvent for sulphur 
in the analysis of black powder. 

Extractions of both flowers of sulphur and brimstone with aniline 
heated to 130° to 140° showed only about 0.05 of 1 per cent insoluble 
material in each. 

a Gody, L., Traite thdorique et pratiquedes mati&resexplosives, 1907,p. 85. Biedermann, R., Chemiker 
Kalender, pt. 1,1910, p. 291. 






























74 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


Several samples of black powder were analyzed, the sulphur being 
determined by means of extraction with hot aniline, and the results 
were compared with those obtained by the usual method of extraction 
with carbon disulphide. The extraction with the aniline was made 
by adding 10-c. c. portions of aniline, previously heated to 130° to 
135° C. to the crucibles containing samples that had been extracted 
with water and dried in the usual manner, the hot aniline being drawn 
through by suction; this treatment was repeated from 5 to 12 times, 
using a total of 50 to 125 c. c. of aniline in different determinations. 
The last portions of aniline were removed by washing with a small 
amount of alcohol, and the residue dried at 100° C. The loss of weight 
was considered as the amount of sulphur present. 

Comparative determinations of sulphur in black powder by extraction with carbon disul¬ 
phide and aniline. 


Sample 

No. 

Sulphur extracted. 

With car¬ 
bon disul¬ 
phide. 

With 

aniline 

(130°). 

1 

13.64 

13.79 

2 

9.99 

9.72 

3 

7.81 

7.74 


Each of the above figures is the average of four to six closely agree¬ 
ing results. This comparison shows that the aniline method gives 
very satisfactory results. Even as small an amount as 50 c. c. of 
aniline was found to be sufficient for complete extraction if each por¬ 
tion was allowed to stand a short time before sucking dry. The aniline 
may be readily recovered by distillation and used repeatedly. 

A series of experiments were made to determine whether any differ¬ 
ence in results would be effected by extracting the sulphur with carbon 
disulphide before the nitrate was extracted with water—that is, an 
inversion of the order of the extractions. A number of samples of 
black powder were analyzed by both methods with the results noted 
in the following tables. For comparison, determinations were made 
of the sulphur by precipitation as barium sulphate after oxidation 
with nitric acid and potassium chlorate. 







BLACK POWDER. 


75 


Results of analyses of black powder. 

[Samples A, B, and C analyzed by C. A. Lambert; sample D analyzed by C. A. Taylor.J 
METHOD 1 (WATER EXTRACTION FIRST). 


Sample. 

Moisture. 

Water 

extract. 

Carbon 

disulphide 

extract. 

Insoluble 

residue. 

Sulphur 
determined 
as BaSO<. 


Per cent. 

Per cent. 

Per cent. 

Per cent. 

Per cent. 


( 0.16 

69. 76 

13.64 

16.44 

| 13.55 


i .16 

69.73 

13.55 

16.56 

B 

/ .21 

74.07 

10.09 

15.63 

| 10.05 

\ -21 

74.27 

9.89 

15.63 


f .36 

78.88 

7.87 

12.89 


c 

\ .36 

78.98 

7.68 

12.98 

\ 7.89 


l .36 

78.91 

7.89 

12.84 



f .47 

73.84 

10.02 

15.67 

I 

D 

\ • 47 

73.74 

10.06 

15.73 

l. 


l .47 

73.79 

10.04 

15.70 

I 


METHOD 2 (CARBON DISULPHIDE EXTRACTION FIRST). 


A 

/ 0.16 

69.58 

13.74 

16.52 

1 io ee 

A 

\ .16 

69.57 

13.80 

16.47 

> 1 0. DO 

T> 

| .21 

73.97 

10.39 

15.43 

1 ia at; 

Jl> 

\ .21 

73.92 

10.44 

15.43 

> JLU. UO 

p 

J .36 

78.45 

8.47 

12. 72 

l 7 CQ 


1 .36 

78.54 

8.49 

12.61 

> /. oJ 


1 -47 

73.91 

10.15 

15.47 

1 

D 

i .47 

73.74 

10.25 

15.54 

\ . 


l -47 

73.82 

10.20 

15.51 

1 


It will be noted that in every case a greater loss was obtained on 
extracting with carbon disulphide when such extraction preceded the 
extraction with water than when it followed the extraction with 
water. That a more correct value for the amount of sulphur present 
is obtained by first removing the water-soluble portion of the powder, 
is shown by the results of the gravimetric determination of sulphur 
as barium sulphate. The latter results agree closely with the loss on 
extraction with carbon disulphide after removal of the nitrate. 

The differences in results noted above are not readily explained. 
That both sodium and potassium nitrates are practically insoluble in 
carbon disulphide was shown by extracting a number of dried samples 
of each of these nitrates with this solvent, losses of only 0.01 to 0.05 
per cent being obtained. It was further demonstrated that the small 
amount of moisture present in the powder samples at the time of the 
extraction with carbon disulphide was not the cause of the high 
results of method 2. This was shown by extracting several samples 
of black powder with carbon disulphide both before and after drying 
in vacuum desiccators. On correcting all results to the sample in 
original condition it was found that the loss on extraction was prac¬ 
tically the same in both cases. The results are shown in the table 
following. 

















76 ANALYSIS OF BLACK POWDER AND DYNAMITE. 

Effect of moisture in black powder on extraction with carbon disulphide before removal 

of nitrate. 

[Determinations by C. A. Taylor.] 


Sample. 

Moisture. 

Loss on extraction with 
carbon disulphide. 

Original 

Desiccated 

Original 

Desiccated 


sample. 

sample. 

sample. 

sample. 


Per cent. 

Per cent. 

Per cent. 

Per cent. 

E 

0.30 


13.82 

13.93 

F 

.22 


10.02 

9.99 

G 

.32 


7.94 

7.92 


The method adopted by the Bureau of Mines for the analysis of 
black powder is as follows: 

BUREAU OF MINES METHOD OF ANALYSIS. 

Moisture is determined by desiccating a 2-gram portion of the 
80-mesh sample spread uniformly on a 3-inch watch glass for three 
days in a sulphuric-acid desiccator. Nitrates are determined by 
extraction with water, sulphur by extraction with carbon disulphide, 
and charcoal by weighing the dried insoluble residue. The soluble 
impurities (sulphates, chlorides, etc.) are determined separately and 
a direct determination of nitrate made by means of the nitrometer. 

In the analysis of black powder, as in the analysis of all other ex¬ 
plosives, the Bureau of Mines follows the standard methods outlined in 
this bulletin except when the presence of unusual constituents renders 
necessary additional separations or determinations or introduces new 
difficulties. As these conditions are seldom met in the analysis of the 
more simple explosives, such as dynamite and gelatin dynamite, but 
are not infrequently found in connection with short-flame explosives 
intended for use in coal mining, they will be taken up in a subsequent 
bulletin, which will consider the analysis of permissible explosives. 












PUBLICATIONS ON MINE ACCIDENTS AND TESTS OF 

EXPLOSIVES. 


The following Bureau of Mines publications may be obtained free 
by applying to the Director, Bureau of Mines, Washington, D. C.: 

Bulletin 10. The use of permissible explosives, by J. J. Rutledge and Clarence 
Hall. 1912. 34 pp., 5 pis. 

Bulletin 15. Investigations of explosives used in coal mines, by Clarence Hall, 
W. O. Snelling, and S. P. Howell, with a chapter on the natural gas used at Pittsburgh, 
by G. A. Burrell, and an introduction by C. E. Munroe. 1911. 197 pp., 7 pis. 

Bulletin 17. A primer on explosives for coal miners, by C. E. Munroe and Clarence 
Hall, 61 pp., 10 pis. Reprint of United States Geological Survey Bulletin 423. 

Bulletin 20. The explosibility of coal dust, by G. S. Rice, with chapters by J. C.W. 
Frazer, Axel Larsen, Frank Haas, and Carl Scholz. 204 pp., 14 pis. Reprint of 
United States Geological Survey Bulletin 425. 

Bulletin 44. First national mine-safety demonstration, Pittsburgh, Pa., October 
30 and 31, 1911, by H. M. Wilson and A. H. Fay, with a chapter on the explosion at 
the experimental mine, by G. S. Rice. 1912. 75 pp., 7 pis. 

Bulletin 46. An investigation of explosion-proof mine motors, by H. H. Clark. 
1912. 44 pp., 6 pis. 

Bulletin 48. The selection of explosives used in engineering and mining opera¬ 
tions, by Clarence Hall and S. P. Howell. 1913. 50 pp., 3 pis. 

Technical Paper 4. The electrical section of the Bureau of Mines, its purpose 
and equipment, by H. H. Clark. 1911. 12 pp. 

Technical Paper 6. The rate of burning of fuse as influenced by temperature and 
pressure, by W. O. Snelling and W. C. Cope. 1912. 28 pp. 

Technical Paper 7. Investigations of fuse and miners’ squibs, by Clarence Hall 
and S. P. Howell. 1912. 19 pp. 

Technical Paper 11. The use of mice and birds for detecting carbon monoxide 
after mine fires and explosions, by G. A. Burrell. 1912. 15 pp. 

Technical Paper 12. The behavior of nitroglycerin when heated, by W. O. Snel¬ 
ling and C, G. Storm. 1912. 14 pp., 1 pi. 

Technical Paper 13. Gas analysis as an aid in fighting mine fires, by G. A. Bur¬ 
rell and F. M. Seibert. 1912. 16 pp. 

Technical Paper 17. The effect of stemming on the efficiency of explosives, by 
W. O. Snelling and Clarence Hall. 1912. 20 pp. 

Technical Paper 18. Magazines and thaw houses for explosives, by Clarence Hall 
and S. P. Howell. 1912. 34 pp., 1 pi. 

Technical Paper 19. The factor of safety in mine electrical installations, by 
H. H. Clark. 1912. 14 pp. 

Technical Paper 21. The prevention of mine explosions; report and recom¬ 
mendations, by Victor Watteyne, Carl Meissner, and Arthur Desborough. 12 pp. 
Reprint of United States Geological Survey Bulletin 369. 

Technical Paper 23. Ignition of mine gas by miniature electric lamps, by H. H. 
Clark. 1912. 5 pp. 


77 



78 


ANALYSIS OF BLACK POWDER AND DYNAMITE. 


Technical Paper 24. Mine fires; a preliminary study, by G. S. Rice. 1912. 
51 pp. 

Technical Paper 28. Ignition of mine gas by standard incandescent lamps, by 
H. H. Clark. 1912. 6 pp. 

Technical Paper 29. Training with mine-rescue breathing apparatus, by J. W. 
Paul. 1912. 16 pp. 

Miners’ Circular 3. Coal-dust explosions, by G. S. Rice. 1911. 22 pp. 
Miners’ Circular 4. The use and care of mine-rescue breathing apparatus, by 
J. W. Paul. 1911. 24 pp. 

Miners’ Circular 5. Electrical accidents in mines; their causes and prevention, 
by H. H. Clark, W. D. Roberts, L. C. Ilsley, and H. F. Randolph. 1911. 10 pp., 3 pis. 

Miners’ Circular 6. Permissible explosives tested prior to January 1, 1912, and 
precautions to be taken in their use, by Clarence Hall. 1912. 20 pp. 

Miners’ Circular 9. Accidents from falls of roof and coal, by G. S. Rice. 1912. 

16 pp. 

Miners’ Circular 10. Mine fires and how to fight them, by J. W. Paul. 1912. 
14 pp. 

Miners’ Circular 11. Accidents from mine cars and locomotives, by L. M. Jones. 
1912. 16 pp. 


INDEX 


A. Page. 


Abel test for stability. See Stability, Abel 
test for. 

Ammonia dynamite, analysis of. 57,58 

constituents of. 57 

Ammonia gelatin dynamite, definition of.... 56 

Ammonium nitrate. See Nitrates. 

Antacid, gravimetric determination of. 47 

Ash, in black powder, determination of.72,73 

Ash, in dynamite, determination of. 50 

B. 

“Bank powder,” composition of. 64 

Berl, K., and Jurrissen, A. W., nitrogen-deter¬ 
mination method of. 63 

Black blasting powder, definition of. 65 

Black powder, analysis of, method of. 76 

composition of. G6 

granulation of, determination of. 66 

sizes of. 67 

moisture in, determination of. 69 

results of analyses of. 75 

sample of, preparation of. 18 

Black powder and gunpowder, difference be¬ 
tween. 66 

“ Blasting gelatin,” composition of. 54 

C. 

Calcium in dynamite, determination of. 46 

Calcium carbonate in dynamite, determina¬ 
tion of. 53 

Cartridge of dynamite, construction of. 13 

volume of, determination of. 8 


Charcoal, in black powder, determination of. 69-72 


Colophony. See Rosin. 

D. 

Densimeter, description of. 68 

figure showing. 68 

Density, absolute, definition of. 67 

determination of apparatus for. 68 

Density, gravimetric, definition of. 67 

determination of. 7,8,67 

Desiccation of dynamite, method of.28,29 

efficiency of agents for. 24 

time required for. 20 

use of sulphuric acid in.20,24 

use of vacuum in.27,28 

without desiccating agent, results of. 26 

Desiccator, Hempel, efficiency of. 21 

Scheibler, efficiency of.21-24 

Dunn, Col. B. W., work of. 9 

Dynamite, analysis of. 7,14 

variations in methods of. 50,51 

results of.51,57 

cartridge of, segregation in. 15 

composition of. 6 

definition of. 6 


Dynamite—Continued. Page. 

moisture in, changes of. 15-16 

determination of. 19 

effect of temperature on.22-23 

figure showing. 23 

methods for. 19 

use of vacuum in. 27 

variations in method of. 52 

Pittsburgh testing station, composition 

of. 5 

qualitative examination of. 16-19 

sample of, preparation of. 12-18 

segregation in. 14 

E. 

Ether, anhydrous, extractive power of.33,34 

as extractive agent, use of.40-41 

Extraction of dynamite with ether. 30 

apparatus for. 30,31 

effect of moisture on.34,3-5 

methods of. 30-33 

Exudation of nitroglycerin, centrifugal test 

for. 9,10 

apparatus used in. 9 

method employed in. 9 

40° test for. 8,9 

pressure test for. 9 

F. 

Fuse powder, description of. 66 

G. 

Gelatin dynamite, composition of. 54 

moisture in, determination of. 54 

nitrocellulose in, determination of. 55 

preparation of sample of. 54 

sulphur in, determination of. 55 

Gody, L., work of. 72 

Gravimetric balance, view of. 32 

Gunpowder, composition of. 66 

H. 

Hempel desiccator, efficiency of. 21 

Hyde, A. L., work of. 40 

I. 

Infusorial earth, view of. 50 

J. 

Judson, E., work of. 64 

Judson powder, composition of. 64 

Jurrissen and Berl, method of. 63 

L. 

Low-freezing explosives, constituents of. 61 

Lunge nitrometer, description of. 35,36 

standardization of. 36,37 

use of. 45 

view of. 36 


79 

























































































80 


INDEX 


M. 

Magnesium in dynamite, determination of... 46 

Merrill, G. P., work of. 49,50 

Moisture in dynamite. See Dynamite, mois¬ 
ture in. 

Moisture in black powder, determination of.. 69 

results of. 70 

Munroe, C. E., work of. 5 

N. 

Nitrates in black powder, calculation of.71,72 

extraction of.70,71 

in dynamite, determination of. 44,53,58-60 

Nitrocellulose, determination of. 55 

Nitroglycerin, absorbents for. 6,49 

classification of. 6 

determination of. 35 

apparatus used in.35,36 

extraction of, with ether. 30 

test for. 16,17 

in low-freezing dynamite, freezing point of 61 
Nitrosubstitution compounds, method of 

determining. 62 

Nitrosubstitution products, color reactions of. 18 
color test for. 17 

P. 

Potassium in black powder, determination of. 71 
Potassium nitrate. See Nitrates. 

R. 

Railroad powder, composition of.. 64 

Reflux-condenser method of extraction.30-32 

Resin in dynamite, determination of...._41,42 

S. 

Scheibler desiccator, efficiency of. 21,24 

Segregation in dynamite. See Dynamite, 
segregation in. 


Sodium nitrate. See Nitrates. 

Specific gravity, apparent, determination of.. 7,8 

Specific gravity, true. See Density, absolute. 


Stability of explosives, Abel test for.10-12 

apparatus used in. 11-12 

time required for. 12 

Starch in dynamite, determination of, appara¬ 
tus for. 43 

method of. 47 

materials included in. 47 

Sulphur in black powder, determination of... 72-74 

effect of temperature on. 70 

in dynamite, determination of. 41,42 

extraction of. 30 

test for. 17 

solubility of, in acetic acid. 42 

T. 

Trinitrotoluene in dynamite, test for. 17 

U. 

Universal tube for nitrometer, advantage of.. 38 

description of. 38 

view of. 36 

W. 

Water. See Moisture. 

Watts, work of. 72 

Wiley extractor, description of. 31 

use of. 31 

view of. 32 

Wood pulp, analyses of.. 48 

determination of. 53 

examination of. 49 

view of. 50 

Wrampelmeier, T. J., work of. 9 

Z. 

Zinc in dynamite, determination of..46,58 


O 


36 4 9 2 


U?8Ji’13 
























































O' -o 


f* |§gj§f ° ifSw* “ ^"V 

,o ° ^y^coootf^ * e 4 o^r* i - ,s v v on° * x *^> e ’°* Q *?^4* * * oo^ : : 

W A °4§®: *>o«° °^ A **M&\ "W 



mi * v 

'»” V^\ VoN °yV 

^ • Jflfe; 

“ " ^ ‘ 




. wUw » * Ipifa i 1 « c ? , % 

: i'° ° 

^ o^Si: *w «ilf>: 


» * 



;*mj'f* %-^.v v ; 

S W • Jft • V* -*^s 


> o 

# o _. t 





V 




^ t 

° *A'»" *^» * * *?\>* 0 °J 




*o A aA <? 

° O 

* <f§>% l 
.& % 0 


W" f 

#*+ t 

* °° V V 


*> <0 'X) 

% 

s A » u j 4> 

, o°v;w%°o 

w fc ^»- < 



o°^>o° ° ^V * * >>.;A 

• *• c ' '. . O fiMOZS, 

' *%. * 


T> 

O * 

* -- ** o 

sU * o kO° Jp 

<v 

* .' 

* * 

.* *V ^ ^ 

^o ^ .-A <T> A 


v. X<* A?* *■ (sA^^/r, 0 <£v v\ 

A# .'H; V 

O 





*»«»’ 4- c 

v.^ „ ^ cv, .o“ „ 
* V A? v 

* \Po eS* 03 


. * ^ V | 

^ cO N «4/<?> ^ ** S LIfi ^°^b y ° * **<£** 

4 %5^v\v^ * W A o ❖ O A * 

°4ffir* Ad* tm&t w 

; * -vo. <su=nc ** * : * 

V;*^Vf.. ,V^£v°! * 0 \> 

*% ^\o,\ >A<k!A A 

AA, liSf/ A A *, 

^ X -^„ ^O „ l - * 




; ^ov 4 ' ° 

o *Oy. t 

4 o° V* 

0 > P *t*O.V*»M*' ^ 





A; .n., 0 *u'°*^ 




* ^ „ 

\ V* z 

* 4^^. °of 
A rA ^ * 

_\<*> , , y c 

rV * * L1 * ^ ^ 
r' O ❖ + O 

. a°/' ' , 

s ' 1 * 4 Vt » 4 * &---''°'A 

W o r ^PS 9 - 

/\llfc /V 1 





i o ■ ^;, c % ^ " ,o^* ;;• CV ° 5 AA c o»=,/V 

; ^ov 4 Ao 4 . #«; W ^ 

* % ^ J»jAV/V!.o % ' • 



?p cl' 


A 



O ^ * 

r - w«ww o 

V^oVx^ A - ’b.* 


v &%:**%** 

V'” °"vA^ * * * o/V M *. ^°°v^5 a° 

^ m®m r aa j ? ,s^, z ^ r 




^ c 




^ /VSi # '<r o°V 



iCKMAN 

DERY INC. 

Ik JUL92 






r <£ *> 

° <s x^ .\ > , <r> a 

% t o»o, ^ 

^ > ^Sk-^ a -1. 


V #Ti4 % * * X ,,;i > 0 / * o 

i^\ : 


N. MANCHESTER, 
INDIANA 46962 


- ''C 


a ° 














































































